Image reading apparatus and method

ABSTRACT

The present invention enables image data with good S/N and high resolution to be obtained reliably in a short reading time. A CCD  102  is formed by arranging line sensors, in which detecting elements having a time integration effect are arranged in a direction orthogonal to a relative movement direction in which the CCD  102  moves relative to an original, in a plurality of columns in the relative movement direction. A signal processing unit  107  detects pixel components on the basis of a model for separating first pixel values obtained in a processing unit time by the CCD  102  into a plurality of the pixel components corresponding to detection positions of the object being detected, and generates second pixel values corresponding to the detection positions of the object being detected on the basis of the detected pixel components. The present invention is applicable to scanners.

TECHNICAL FIELD

The present invention relates to an apparatus and a method for imagereading, and particularly to an apparatus and a method for image readingthat read an image of an object being detected.

BACKGROUND ART

Scanners are widely used which read an image of an original as a subjectsuch as paper, a photograph or the like and generate image datacorresponding to the image. A CCD or the like is used in a scanner.

Such a scanner repeats control such that after the CCD reads an image ofa predetermined area of an original, the CCD is moved and a shutter ofthe CCD is operated so as not to pick up an image of another area of theoriginal, and when the CCD reaches a next area to be read of theoriginal, the shutter of the CCD is operated so as to pick up an image.Thereby images of desired areas of the original are read.

In order to improve resolution, however, the shutter needs to beoperated so as to pick up only an image at a predetermined position of anarrower area of the subject in response to movement of the CCD in ascanning direction, thus resulting in a problem of a shorter imagepickup time of the CCD and hence a degraded S/N of image data obtained.In order to shorten reading time, the shutter needs to be operated so asto pick up an image in a shorter exposure time in response to movementof the CCD in the scanning direction, thus resulting in a problem of ashorter image pickup time of the CCD and hence similarly a degraded S/Nof image data obtained.

In addition, in image pickup by a mechanical shutter, the shutter needsto be opened and closed frequently in response to movement of thedetecting element, thus resulting in a problem of increased load on themechanism and hence susceptibility to failures. In this case, there isalso a problem of increased power consumption when the mechanicalshutter is operated frequently.

Furthermore, in order to lengthen image pickup time simply for higherS/N of image data, the CCD needs to be stopped at each image pickupposition of the subject, thus resulting in a problem of long readingtime.

DISCLOSURE OF INVENTION

The present invention has been made in view of such a situation, and itis accordingly an object of the present invention to be able to reliablyobtain image data with good S/N and higher resolution in a short readingtime.

According to the present invention, there is provided an image readingapparatus including: reading means formed by arranging line sensors, inwhich detecting elements having a time integration effect are arrangedin a direction orthogonal to a relative movement direction in which thereading means moves relative to an object being detected, in a pluralityof columns in the relative movement direction; pixel component detectingmeans for detecting pixel components on the basis of a model forseparating first pixel values obtained in a processing unit time by thedetecting elements into a plurality of the pixel componentscorresponding to detection positions of the object being detected; andpixel value generating means for generating second pixel valuescorresponding to the detection positions of the object being detected onthe basis of the pixel components detected by the pixel componentdetecting means.

The pixel component detecting means can include model generating meansfor generating the model that represents a relation between the firstpixel values and a plurality of the pixel components corresponding tothe detection positions, the pixel components being accumulated in eachdivided unit time obtained by dividing the processing unit time by anumber of columns of the line sensors; and the pixel component detectingmeans can detect the pixel components on the basis of the modelgenerated by the model generating means.

The image reading apparatus can further include speed detecting meansfor detecting relative speed between the detecting elements and theobject being detected; and the model generating means can generate themodel that represents a relation between the first pixel values obtainedfrom a part of the detecting elements of the line sensors arranged inthe reading means and the pixel components in correspondence with therelative speed detected by the speed detecting means.

The image reading apparatus can further include speed detecting meansfor detecting relative speed between the detecting elements and theobject being detected; and the model generating means can generate themodel that represents a relation between third pixel values obtained byadding together the first pixel values obtained from adjacent detectingelements of a plurality of the detecting elements arranged in columns inthe relative movement direction of the reading means and the pixelcomponents in correspondence with the relative speed detected by thespeed detecting means.

The image reading apparatus can further include control means forcontrolling the reading means such that when the reading means ispositioned at an initial position, the reading means picks up an imageof the object being detected and outputs the first pixel valuescorresponding to the detecting elements in a state of standing stillwith respect to the object being detected during the processing unittime; and the pixel component detecting means can detect other pixelcomponents by substituting the pixel components generated on the basisof the first pixel values resulting from image pickup by the readingmeans in the state of standing still with respect to the object beingdetected under control of the control means into the model thatrepresents the relation between the first pixel values and a pluralityof the pixel components corresponding to the detection positions.

The control means can control the reading means such that the readingmeans picks up an image of the object being detected and outputs thefirst pixel values corresponding to the detecting elements in the stateof standing still with respect to the object being detected during theprocessing unit time at predetermined time intervals.

The image reading apparatus can further include control means forcontrolling exposure time for each of the detecting elements of thereading means such that each of the first pixel values includes thepixel component corresponding to a different position in the relativemovement direction of the object being detected; and the pixel componentdetecting means can detect the pixel components on the basis of themodel that represents a relation between the first pixel values eachincluding the pixel component corresponding to a different position inthe relative movement direction of the object being detected and aplurality of the pixel components corresponding to the detectionpositions.

The control means can control the exposure time for each of thedetecting elements of the reading means such that each of the firstpixel values includes the pixel component corresponding to a differentposition in the relative movement direction of the object being detectedat predetermined time intervals.

The image reading apparatus can further include moving means for movingone of the object being detected and the reading means so as to change arelative position between the object being detected and the readingmeans.

The pixel component detecting means can include normal equationgenerating means for generating a normal equation on the basis of amodel for separating first pixel values obtained by the detectingelements into a plurality of pixel components corresponding to detectionpositions of the object being detected; and the pixel componentdetecting means can detect the pixel components on the basis of thenormal equation generated by the normal equation generating means.

The image reading apparatus can further include first control means forcontrolling image pickup of the reading means such that each of thedetecting elements arranged in a plurality of columns in the relativemovement direction begins exposure at an identical first position of thedetection positions of the object being detected and ends exposure at anidentical second position different from the first position; and secondcontrol means for controlling the image pickup of the reading means suchthat the detecting elements begin exposure after ending exposure at athird time between a first time when all of the detecting elementsarranged in the plurality of columns have reached the first position andhave begun exposure and a second time when one of the detecting elementsarranged in the plurality of columns has reached the second position andhas ended the exposure; wherein the normal equation generating means cangenerate the normal equation by setting the first pixel values obtainedby the detecting elements in the normal equation representing a relationbetween a plurality of the pixel components including the pixelcomponent corresponding to one of the first position, the secondposition, and a third position as a detection position at the third timeand the first pixel values.

The normal equation generating means can generate the normal equationfor calculating the pixel components by applying a method of leastsquares.

The normal equation generating means can generate the normal equationweighted in correspondence with lengths of exposure times for obtainingthe first pixel values.

According to the present invention, there is provided an image readingmethod including: a pixel component detecting step for detecting pixelcomponents on the basis of a model for separating first pixel valuesobtained in a processing unit time by detecting elements into aplurality of the pixel components corresponding to detection positionsof an object being detected; and a pixel value generating step forgenerating second pixel values corresponding to the detection positionsof the object being detected on the basis of the pixel componentsdetected by processing of the pixel component detecting step.

According to the present invention, there is provided a program on astorage medium including: a pixel component detecting step for detectingpixel components on the basis of a model for separating first pixelvalues obtained in a processing unit time by detecting elements into aplurality of the pixel components corresponding to detection positionsof an object being detected; and a pixel value generating step forgenerating second pixel values corresponding to the detection positionsof the object being detected on the basis of the pixel componentsdetected by processing of the pixel component detecting step.

According to the present invention, there is provided a program executedby a computer, the program including: a pixel component detecting stepfor detecting pixel components on the basis of a model for separatingfirst pixel values obtained in a processing unit time by detectingelements into a plurality of the pixel components corresponding todetection positions of an object being detected; and a pixel valuegenerating step for generating second pixel values corresponding to thedetection positions of the object being detected on the basis of thepixel components detected by processing of the pixel component detectingstep.

Pixel components are detected on the basis of a model for separatingfirst pixel values obtained in a processing unit time by detectingelements into a plurality of the pixel components corresponding todetection positions of an object being detected, and second pixel valuescorresponding to the detection positions of the object being detectedare generated on the basis of the detected pixel components.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a configuration of an embodiment of ascanner, or an image reading apparatus according to the presentinvention;

FIG. 2 is a diagram showing an example of configuration of a flatbedscanner;

FIG. 3 is a block diagram showing a more detailed functionalconfiguration of an image reading apparatus according to the presentinvention;

FIG. 4 is a block diagram showing a functional configuration of a signalprocessing unit 107;

FIG. 5 is a block diagram showing a functional configuration of amovement blur removing unit 154;

FIG. 6 is a diagram schematically showing a relation between a CCD 201of a conventional scanner and an original 21;

FIG. 7 is a diagram schematically showing a relation between the CCD 201of the conventional scanner and the original 21;

FIG. 8 is a diagram of assistance in explaining movement blur;

FIG. 9 is a diagram of assistance in explaining movement blur;

FIG. 10 is a diagram of assistance in explaining change in an amount ofmovement blur;

FIG. 11 is a diagram of assistance in explaining change in the amount ofmovement blur;

FIG. 12 is a diagram schematically showing a relation between a CCD 102of a scanner according to the present invention and an original 21;

FIG. 13 is a diagram schematically showing a relation between the CCD102 of the scanner according to the present invention and the original21;

FIG. 14 is a diagram of assistance in explaining signals outputted bythe CD 102;

FIG. 15 is a diagram of assistance in explaining signals outputted bythe CD 102;

FIG. 16 is a diagram showing an example of image components included inthe signals outputted by the CCD 102 when the CCD 102 stands still;

FIG. 17 is a diagram showing an example of image components included inthe signals outputted by the CCD 102 when the CCD 102 moves;

FIG. 18 is a diagram of assistance in explaining a concrete example ofprocessing for obtaining known values and breaking a chain of effects oferrors;

FIG. 19 is a diagram illustrating another concrete example of processingfor obtaining known values and breaking a chain of effects of errors;

FIG. 20 is a diagram of assistance in explaining a read area of anoriginal 21;

FIG. 21 is a diagram of assistance in explaining signals outputted bythe CCD 102;

FIG. 22 is a diagram showing an example of image components included inthe signals outputted by the CCD 102;

FIG. 23 is a diagram of assistance in explaining a concrete example ofprocessing for obtaining known values and breaking a chain of effects oferrors;

FIG. 24 is a diagram showing an example of image components included inthe signals outputted by the CCD 102;

FIG. 25 is a diagram of assistance in explaining a concrete example ofprocessing for obtaining known values and breaking a chain of effects oferrors;

FIG. 26 is a diagram showing an example of image components included inthe signals outputted by the CCD 102;

FIG. 27 is a diagram of assistance in explaining a concrete example ofprocessing for obtaining known values and breaking a chain of effects oferrors;

FIG. 28 is a flowchart of assistance in explaining reading processing;

FIG. 29 is a flowchart of assistance in explaining image signalprocessing;

FIG. 30 is a flowchart of assistance in explaining movement blur removalprocessing;

FIG. 31 is a block diagram showing a functional configuration of amovement blur removing unit 154;

FIG. 32 is a diagram of assistance in explaining a concrete example ofprocessing for controlling timing of shutters of the CCD 102 for eachdetecting element and calculating image components;

FIG. 33 is a diagram of assistance in explaining the concrete example ofprocessing for controlling the timing of the shutters of the CCD 102 foreach detecting element and calculating the image components;

FIG. 34 is a diagram of assistance in explaining another concreteexample of processing for controlling timing of the shutters of the CCD102 for each detecting element and calculating image components;

FIG. 35 is a diagram of assistance in explaining the other concreteexample of processing for controlling the timing of the shutters of theCCD 102 for each detecting element and calculating the image components;

FIG. 36 is a flowchart of assistance in explaining movement blur removalprocessing;

FIG. 37 is a diagram showing a configuration of another embodiment of ascanner according to the present invention;

FIG. 38 is a diagram showing a configuration of a further embodiment ofa scanner according to the present invention; and

FIG. 39 is a diagram showing a configuration of a further embodiment ofa scanner according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

A scanner is an image reading apparatus that reads informationcorresponding to positions of pixels and spectral reflectance (orspectral transmittance) of an image from the image formed astwo-dimensional information on an original such as a paper, a photographor the like, which is an example of a detected object, converts the readinformation into digital data, and outputs the digital data to aninformation processing apparatus such as a computer or the like.

The scanner comprises an illuminating light source, an optical system, alinear image sensor (line sensor) and the like. The scanner alsocomprises a reading unit for performing main scanning, a carrying systemfor performing sub-scanning, and a signal processing unit for performingprocessing such as data compression and the like.

Directing attention to sub-scanning, scanners using a linear imagesensor are classified into sheet feed scanners, flatbed scanners,hand-held scanners, and film scanners.

In a sheet feed scanner, a reading unit is fixed, and an original iscarried by a carrying system, whereby sub-scanning is performed.

In a flatbed scanner, an original is fixed, and an optical system and areading unit move, thus performing sub-scanning.

Sub-scanning of a hand-held scanner is performed by a user holding abody of the hand-held scanner and moving the hand-held scanner withrespect to an original.

A film scanner is exclusively for photographic films (such as so-called35-mm films, APS (the Advanced Photographic System) or the like), andreads an image by transmission.

FIG. 1 is a diagram showing a configuration of an embodiment of ascanner, or an image reading apparatus according to the presentinvention. The scanner shown in FIG. 1 is a so-called sheet feedscanner.

A linear image sensor 11 obtains reflected light (or transmitted light)from a narrow line-shaped area, for example an area being read in FIG. 1of an original 21 as an example of a detected object illuminated by anilluminating light source 16 via an optical system comprising a lens 12and the like. The linear image sensor 11 is for example a device formedby arranging detecting elements in a form of a line in a direction ofmain scanning in FIG. 1 and comprises a CCD (Charge Coupled Device), aCMOS (Complementary Metal-oxide Semiconductor) sensor or the like.

The linear image sensor 11 supplies a signal corresponding to theobtained reflected light to a processing unit 13. That is, the linearimage sensor 11 reads an image of the original 21 and supplies a signalcorresponding to the read image to the processing unit 13.

The original 21 is fed at a predetermined speed by a roller 14 on thebasis of driving force supplied from a carrying system 15. Therefore theposition of the original 21 relative to the lens 12 and the linear imagesensor 11 is gradually shifted. The linear image sensor 11 obtainsreflected light from a next area in response to the movement of theoriginal 21, and then supplies a signal corresponding to an image of thenext area to the processing unit 13.

In FIG. 1, A denotes the area being read, and B denotes the area to beread next.

The linear image sensor 11 repeats the processing of reading an image ofa predetermined area of the original 21 in response to the movement ofthe original 21, and sequentially supplies a signal of the image to theprocessing unit 13 in response to the reading processing.

Since the original 21 is carried at a predetermined speed, an imagesignal outputted by the linear image sensor 11 includes a movement blur.

The lens 12 refracts light reflected by an image reading area of theoriginal 21, and thereby forms an image corresponding to the readingarea of the original 21 on the linear image sensor 11.

The processing unit 13 generates image data as digital data without amovement blur on the basis of the signal corresponding to the imagewhich signal is supplied from the linear image sensor 11, and outputsthe generated image data to an information processing apparatus such asa computer not shown in the figure or the like.

FIG. 2 is a diagram showing a configuration of another embodiment of ascanner, or an image reading apparatus according to the presentinvention. The scanner shown in FIG. 2 is a so-called flatbed scanner.

The same parts as shown in FIG. 1 are identified by the same referencenumerals, and description thereof will be omitted.

An original platen 41 is made of a transparent flat glass, plastic orthe like. An original 21 is placed on the original platen 41 such thatan image to be read faces a scanning unit 42. The original 21 placed onthe original platen 41 is fixed to a body 31.

The scanning unit 42 comprises an optical system, a linear image sensor11 and the like. When reading an image of the original 21, the scanningunit 42 is moved by a driving unit not shown from the left to the rightof FIG. 2, for example, at a predetermined speed with respect to theoriginal platen 41, that is, the original 21.

The scanning unit 42 comprises the linear image sensor 11, which is aline sensor, a lens 12, an illuminating light source 16, a mirror 51, amirror 52, a mirror 53 and the like.

The mirror 51, the mirror 52, and the mirror 53 reflect light appliedfrom the illuminating light source 16 and reflected from the original 21via the original platen 41, and thereby makes the light incident on thelinear image sensor 11 via the lens 12.

When the linear image sensor 11 is smaller than a reading area of theoriginal 21, the optical system is a reducing optical system, and animage formed by the light incident on the linear image sensor 11 isreduced as compared with an image of the original.

On the other hand, when the linear image sensor 11 is of a substantiallyequal length to that of a reading area of the original 21, the opticalsystem is an unmagnification optical system using a rod lens array orthe like as the lens 12, and an image formed by the light incident onthe linear image sensor 11 is of an equal length to that of an image ofthe original 21.

When a regular reflection component of the light applied from theilluminating light source 16 is incident from a glossy original 21 onthe linear image sensor 11, detecting elements are saturated, so thatthe linear image sensor 11 cannot read the image. Thus, an optical axisof the optical system is set such that the regular reflection componentof the light applied from the illuminating light source 16 is notincident on the linear image sensor 11.

Since the scanning unit 42 including the linear image sensor 11 obtainsthe image of the original 21 while moving at a predetermined speed, asignal supplied from the scanning unit 42 to a signal processing unit 13includes movement blur. The movement blur will be described later indetail.

The optical system is set such that the light incident on the linearimage sensor 11 is bright and uniform. As a factor that impairsbrightness and uniformity of the light incident on the linear imagesensor 11, there is light distribution of the illuminating light source16, a COS4 law of the optical system, vignetting of the lens 12 or thelike.

The light distribution of the illuminating light source 16 often becomesa problem especially in regard to light incident on both edges of thelinear image sensor 11. The COS4 law of the optical system indicatesthat brightness of a peripheral field of view of the optical system isdecreased in proportion to cos4 θ. The vignetting refers to shading of aluminous flux at an edge of the lens 12 or the like, which results indecrease in the brightness.

The light distribution of the illuminating light source 16, the COS4 lawof the optical system, the vignetting of the lens 12 and the like causedarker light on the periphery of the linear image sensor 11 as comparedwith light at a center of the linear image sensor 11.

In order to prevent the darker light on the periphery of the linearimage sensor 11 as compared with the light at the center of the linearimage sensor 11, optical shading correction is performed to reduce anamount of light at the center, and consequently an amount of light on animage plane is made as uniform as possible, for example.

The processing unit 13 includes an A/D (Analog/Digital) converter unit,an embedded computer, a DSP (Digital Signal Processor) or the like. Theprocessing unit 13 generates image data as digital data without amovement blur on the basis of a signal corresponding to an image whichsignal is supplied from the linear image sensor 11, and outputs thegenerated image data to an information processing apparatus such as acomputer not shown in the figure or the like.

The scanner according to the present invention can be a color scanner.

A color scanner performs color separation of an original. Colorseparation methods are roughly classified into a light source changingmethod, a filter changing method, and a color linear image sensormethod.

In the light source changing method, three fluorescent lampscorresponding to separated colors and serving as the illuminating lightsource 16 are blinked sequentially, and a monochrome linear image sensor11 sequentially reads an image of an original 21, whereby a red, agreen, and a blue signal output are obtained.

In the filter changing method, a red, a green, and a blue color filterare provided between the illuminating light source 16 and the linearimage sensor 11, and the color filters are changed, whereby a red, agreen, and a blue signal output are obtained.

In the color linear image sensor method, a color image sensor formed byincorporating a linear image sensor with three lines as one unit andcolor filters into one package performs color separation and readingsimultaneously.

FIG. 3 is a block diagram showing a more detailed functionalconfiguration of an image reading apparatus according to the presentinvention.

An iris 101 reduces an amount of light entering a CCD 102 via a lens 12according to intensity of the light.

The CCD 102 corresponds to the linear image sensor 11. The CCD 102generates a signal corresponding to the incident light on the basis of adriving signal supplied from a timing generator 103, and then suppliesthe generated signal to a gain adjustment/noise suppression unit 104.

In the CCD 102, photodiodes as photosensitive units arranged in a formof a line (one dimension) convert energy of the incident light intocharge, and a shift electrode transfers the charge to a CCD analogregister. The photodiodes of the CCD 102 correspond to the detectingelements. The CCD 102 sequentially converts the energy of the incidentlight into charge and accumulates the converted charge withoutdischarging the charge in an exposure time. The CCD 102 can therefore besaid to have a time integration effect. The exposure time corresponds toa processing unit time.

The CCD analog register serving as a transfer unit in the CCD 102sequentially transfers the transferred charge to an output unit usuallyby a two-phase clock pulse included in the driving signal. The outputunit of the CCD 102 converts the charge into voltage.

That is, the CCD 102 converts light detected by the N photosensitiveunits arranged in the form of a line into N voltage signals, and thenoutputs the analog voltage signals.

For colorization, the CCD 102 may include a color filter for each ofthree lines as one package. Efforts have been continued for highersensitivity, lower noise, higher speed, higher resolution, and lowerpower consumption of the CCD 102.

The gain adjustment/noise suppression unit 104 adjusts level of thesignal supplied from the CCD 102, and applies processing such ascorrelated double sampling to the signal to thereby suppress noiseincluded in the signal. Correlated double sampling utilizes a strongcorrelation of noise included in a signal period with noise included ina field-through zero-level period, and is effective especially insuppressing reset noise.

The gain adjustment/noise suppression unit 104 supplies a signal with anadjusted signal level and suppressed noise to an A/D conversion unit105.

The A/D conversion unit 105 subjects the signal supplied from the gainadjustment/noise suppression unit 104 to analog/digital conversion, andthen supplies an image signal as a digital signal to a memory 106.

The memory 106 sequentially stores the image signal supplied from theA/D conversion unit 105, and constructs image data corresponding to theoriginal 21. The memory 106 supplies the image data to a signalprocessing unit 107.

The signal processing unit 107 applies defect correction processing,white balance adjustment processing and the like to the image datacorresponding to the original 21 which image data is supplied from thememory 106, and also removes movement blur included in the image data.The signal processing unit 107 supplies resulting image data to a datatransmission unit 109. In applying the defect correction processing,white balance adjustment processing, and movement blur removalprocessing, the signal processing unit 107 temporarily stores image datain a memory 108, and applies the processing to the image data stored inthe memory 108.

The data transmission unit 109 temporarily stores the image signalsupplied from the signal processing unit 107 in a memory 110, andtransmits the image data stored in the memory 110 to an externalapparatus by a predetermined method.

On the basis of an external control signal supplied externally, a mainCPU 111 controls light emission of an illuminating light source 16,generation of a driving signal by the timing generator 103, theprocessing of the gain adjustment/noise suppression unit 104, processingof a controller 112, and operation of a motor 113. For example, the mainCPU 111 makes the timing generator 103 drive an electronic shutter foreach pixel of the CCD 102, which will be described later. Also, forexample, the main CPU 111 realizes relative movement between theoriginal 21 and the linear image sensor 11, which will be describedlater, by controlling a unit for driving the carrying system 15 or thescanning unit 42.

The main CPU 111 obtains data indicating relative speed between theoriginal 21 and the CCD 102 from the unit for driving the carryingsystem 15 or the scanning unit 42. The main CPU 111 supplies the dataindicating the relative speed between the original 21 and the CCD 102 tothe signal processing unit 107 via the controller 112.

The controller 112 controls the operation of the signal processing unit107 and the operation of the data transmission unit 109 under control ofthe main CPU 111.

The motor 113 drives the iris 101 and adjusts a diaphragm of the iris101 under control of the main CPU 111.

A power supply unit 114 supplies the CCD 102 to an interface 115 withpower necessary for respective operations of the CCD 102 to theinterface 115.

Further, the main CPU 111 is connected with a drive 121 via theinterface 115. The drive 121 reads a program or data recorded (stored)on a magnetic disk 131, an optical disk 132, a magneto-optical disk 133,or a semiconductor memory 134 mounted in the drive 121, and thensupplies the read program or data to the main CPU 111 via the interface115.

The main CPU 111 executes the program supplied from the drive 121 orsupplies the program to the controller 112 or the signal processing unit107.

FIG. 4 is a block diagram showing a functional configuration of thesignal processing unit 107.

A defect correction unit 151 detects a position of a flawed or defectivepixel of input image data which position corresponds to a pixel thatdoes not react to light or has charge at all times among pixels of theCCD 102, and corrects the flawed or defective pixel by setting anadjacent pixel value in the flawed or defective pixel, for example. Thedefect correction unit 151 supplies the image data resulting from thecorrection of the flawed or defective pixel to a clamp unit 152.

The clamp unit 152 sets a setup level of a luminance signal of the imagedata, and then supplies the image data with the set setup level to awhite balance unit 153. The data outputted by the A/D conversion unit105 is shifted in a positive direction so as to prevent the cutting ofnegative values. The clamp unit 152 brings back the data by the amountof-shift so that the image data includes correct negative values.

The white balance unit 153 adjusts RGB (Red, Green, Blue) gain incorrespondence with a predetermined color temperature, and therebyadjusts white balance of the image data. The white balance unit 153supplies the image data with the adjusted white balance to a movementblur removing unit 154.

Incidentally, a scanner for color images requires the white balance unit153, but a scanner for monochrome images does not require the whitebalance unit 153.

The movement blur removing unit 154 removes movement blur included inthe image data, and then supplies the image data without movement blurto a gamma correction unit 155. A configuration of the movement blurremoving unit 154 and movement blur removal processing by the movementblur removing unit 154 will be described later in detail.

The gamma correction unit 155 applies to the image data a gammacorrection for adjusting level of the image data corresponding tointensity of light of the CCD 102 according to a predetermined gammacurve.

Incidentally, because the gamma correction is nonlinear processing, itis desirable that when linear processing is applied to the image data,the linear processing be applied before the gamma correction. Themovement blur removal processing by the movement blur removing unit 154is linear processing.

The gamma correction unit 155 supplies the gamma-corrected image data toan image quality adjustment unit 156.

The image quality adjustment unit 156 applies processing for visuallyimproving the image, for example contour correction processing and otherimage quality adjustment processing to the image data, and then suppliesthe image data adjusted in image quality to a color space conversionunit 157.

The color space conversion unit 157 converts a color space according toan output format of the image data (for example determines the positionof chromaticity coordinates of three primary color points in a colorspace), and then outputs the color space-converted image data.

FIG. 5 is a block diagram showing a functional configuration of themovement blur removing unit 154.

A processing unit extracting unit 171 extracts a processing unitcomprising predetermined pixels of the image data in correspondence withtiming of electronic shutters of the CCD 102 or the like. The processingunit extracting unit 171 supplies the extracted processing unit to amodeling unit 172.

The modeling unit 172 generates a model on the basis of the processingunit supplied from the processing unit extracting unit 171, and thensupplies the processing unit together with the generated model to anequation constructing unit 173. The model generated by the modeling unit172 for example indicates the number of pixels of the image datagenerated as a result of removing movement blur and the number of pixelsincluded in the processing unit.

The equation constructing unit 173 constructs equations as simultaneousequations for calculating pixel values of the image data free frommovement blur on the basis of the model and the processing unit suppliedfrom the modeling unit 172. The equation constructing unit 173 suppliesthe constructed equations to a simultaneous equation calculating unit174.

The simultaneous equation calculating unit 174 solves the equationssupplied from the equation constructing unit 173, thereby calculates thepixel values of the image data free from movement blur, and then outputsthe calculated pixel values of the image data.

The movement blur of the image data will be described with reference toFIGS. 6 to 11.

FIG. 6 and FIG. 7 are diagrams schematically showing a relation betweena CCD 201 of a conventional scanner and an original 21.

The CCD 201 has detecting elements arranged in one line.

As shown in FIG. 6, when the CCD 201 obtains an image of the original21, the CCD 201 moves relative to a surface showing the image of theoriginal 21 in parallel with the surface in one predetermined direction.When the surface showing the image of the original 21 corresponds to anx-axis and a y-axis, for example, the CCD 201 moves in a direction ofthe x-axis. (In practice, when obtaining the image of the original 21, areading area of the CCD 201 moves on the surface showing the image ofthe original 21 relative to the original 21 in one predetermineddirection.)

As shown in FIG. 7, the CCD 201 obtains an image of the original 21 incorrespondence with length of one pixel of a photodiode or the like in atraveling direction.

FIG. 8 and FIG. 9 are diagrams of assistance in explaining movementblur.

When the CCD 201 repeats a movement and stop for each length of onepixel and performs reading (accumulation of charge in photodiodes)during a stop, the read image does not include movement blur, as shownin FIG. 8.

However, such a reading method is not practical because reading cannotbe performed during a time of movement and therefore an enormous amountof time is required to read the original 21.

On the other hand, when the CCD 201 moves at a constant speed relativeto the original 21, as shown in FIG. 9, the CCD 201 moves even during atime when the CCD 201 accumulates charge in the photodiodes (exposuretime) and hence the CCD 201 reads, as an image corresponding to onepixel, a larger area of the original as compared with the length of onepixel of the CCD.

In such a case, movement blur can be reduced by shortening the chargeaccumulation time. In general, however, the shortening of the chargeaccumulation time lowers S/N of the image data, and therefore theaccumulation time is made as long as possible.

Since the relative position of the CCD 201 and the original 21 ischanged at all times, it is considered that instead of reading data forone pixel in one shutter operation, components of adjacent pixels aremixed with each other. It may be said, however, that considering thefact that a normal CCD performs processing for mixing components ofadjacent pixels with each other by an optical low-pass filter to preventfolding, the mixing to some extent of adjacent pixels with each other asa result of movement blur doest not present a problem.

However, when the extent of the mixing of adjacent pixels with eachother is to be limited, the traveling speed of the CCD 201 needs to belimited at the same time, and therefore high-speed reading becomesdifficult.

FIG. 10 and FIG. 11 are diagrams of assistance in explaining change inan amount of movement blur which change corresponds to change inrelative speed between the CCD 201 and the original 21.

When length of a read area of the original which length corresponds tomovement in an exposure time is twice length of one pixel of the CCD, apixel value of image data corresponding to one pixel of the CCD coversan image of an area of twice the length of one pixel of the CCD in thedirection of the x-axis, as shown in FIG. 10.

Similarly, when length of a read area of the original which lengthcorresponds to movement in an exposure time is three times the length ofone pixel of the CCD, a pixel value of image data corresponding to onepixel of the CCD covers an image of an area of three times the length ofone pixel of the CCD in the direction of the x-axis, as shown in FIG.11.

The image reading apparatus according to the present invention removesmovement blur from image data. Thereby, even when the CCD 201 movesrelative to the original 21 at a constant speed and length of a readarea of the original which length corresponds to movement in an exposuretime is longer than the length of one pixel of the CCD, the imagereading apparatus according to the present invention provides a pixelvalue of an area of the original which area corresponds to the length ofone pixel of the CCD.

Image signals outputted by the CCD 102 of the image reading apparatusaccording to the present invention will next be described with referenceto FIG. 12 and FIG. 13.

FIG. 12 and FIG. 13 are diagrams schematically showing a relationbetween the CCD 102 of the scanner according to the present inventionand an original 21.

The CCD 201 has elements such as photodiodes arranged in four lines inthe direction of movement relative to the original 21.

As shown in FIG. 12, when the CCD 102 obtains an image of the original21, the CCD 102 moves relative to a surface showing the image of theoriginal 21 in parallel with the surface in one predetermined direction.When the surface showing the image of the original 21 corresponds to anx-axis and a y-axis, for example, the CCD 102 moves in a direction ofthe x-axis. (In practice, when obtaining the image of the original 21, areading area of the CCD 102 moves on the surface showing the image ofthe original 21 relative to the original 21 in one predetermineddirection.)

The direction of the x-axis corresponds to the direction of the relativemovement.

As shown in FIG. 13, the CCD 102 moves at a speed v0 in a travelingdirection indicated by an arrow in the figure. The CCD 102 obtains animage of the original 21 in correspondence with length of one pixel ofthe photodiodes or the like arranged in four columns in the travelingdirection. For example, the CCD 102 obtains the image of the original 21in each of a pixel P0, a pixel P1, a pixel P2, and a pixel P3.

FIG. 14 is a diagram of assistance in explaining signals outputted bythe CCD 102 when length of a read area of the original 21 moved in anexposure time is four times the length of one pixel of a photodiode orthe like.

Each of image areas A0 to A10 of the original 21 in FIG. 14 correspondsto length of one pixel of the CCD 102. The image areas of the original21 which areas each correspond to the length of one pixel of the CCD 102are represented with consecutive numbers as A0, A1, A2 to An.

A signal corresponding to the pixel P0 of the CCD 102 covers an image ofa read area of the original 21 which area is of four times the length ofone pixel of the CCD 102. Each of signals corresponding to the pixels P1to P3 of the CCD 102 covers an image of a read area of the original 21which area is of four times the length of one pixel of the CCD 102.

For example, when the pixel P0 of the CCD 102 starts exposure at theimage area A0 of the original 21 and ends the exposure at the image areaA3 of the original 21, the signal corresponding to the pixel P0 of theCCD 102 (corresponding to a pixel value in image data) includescomponents a0 to a3 of the images A0 to A3, respectively, of theoriginal 21. The components of the images correspond to pixelcomponents.

When the pixel P1 of the CCD 102 starts exposure at the image area A1 ofthe original 21 and ends the exposure at the image area A4 of theoriginal 21, the signal corresponding to the pixel P1 of the CCD 102(corresponding to a pixel value in image data) includes components a1 toa4 of the images A1 to A4, respectively, of the original 21.

When the pixel P2 of the CCD 102 starts exposure at the image area A2 ofthe original 21 and ends the exposure at the image area A5 of theoriginal 21, the signal corresponding to the pixel P2 of the CCD 102(corresponding to a pixel value in image data) includes components a2 toa5 of the images A2 to A5, respectively, of the original 21.

When the pixel P3 of the CCD 102 starts exposure at the image area A3 ofthe original 21 and ends the exposure at the image area A6 of theoriginal 21, the signal corresponding to the pixel P3 of the CCD 102(corresponding to a pixel value in image data) includes components a3 toa6 of the images A3 to A6, respectively, of the original 21.

The movement blur removal processing will next be described withreference to FIGS. 15 to 18.

FIG. 15 is a diagram of assistance in explaining signals outputted bythe CCD 102.

Letting t0 be an exposure time, in an exposure time t0 from a time 0 toa time t0, a signal corresponding to the pixel P0 of the CCD 102 is b0;a signal corresponding to the pixel P1 of the CCD 102 is b1; a signalcorresponding to the pixel P2 of the CCD 102 is b2; and a signalcorresponding to the pixel P3 of the CCD 102 is b3.

Letting t0 be an exposure time, in an exposure time t0 from the time t0to a time 2*t0 (time at which twice t0 passes from the time 0), a signalcorresponding to the pixel P0 of the CCD 102 is b4; a signalcorresponding to the pixel P1 of the CCD 102 is b5; a signalcorresponding to the pixel P2 of the CCD 102 is b6; and a signalcorresponding to the pixel P3 of the CCD 102 is b7.

Letting t0 be an exposure time, in an exposure time t0 from the time2*t0 to a time 3*t0 (time at which three times t0 passes from the time0), a signal corresponding to the pixel P0 of the CCD 102 is b8; asignal corresponding to the pixel P1 of the CCD 102 is b9; a signalcorresponding to the pixel P2 of the CCD 102 is b10; and a signalcorresponding to the pixel P3 of the CCD 102 is b11.

Similarly, letting t0 be an exposure time, in an exposure time t0 fromthe time 3*t0 to a time 4*t0 (time at which four times t0 passes fromthe time 0), a signal corresponding to the pixel P0 of the CCD 102 isb12; a signal corresponding to the pixel P1 of the CCD 102 is b13; asignal corresponding to the pixel P2 of the CCD 102 is b14; and a signalcorresponding to the pixel P3 of the CCD 102 is b15.

The times t0, 2*t0, 3*t0, and 4*t0 in FIG. 15 correspond to timing oftransmission of charge accumulated in the CCD 102. The transmission timeis sufficiently short as compared with the exposure time.

FIG. 16 is a diagram showing an example of image components included inthe signals outputted by the CCD 102 when the CCD 102 stands still withthe pixel p0 corresponding to the area a0.

Consideration will be given to dividing the exposure time into fourequal lengths. A divided period of the exposure time corresponds to adivided unit time.

In a first period of the four divided periods of the exposure time t0from the time 0 to the time t0, the pixel P0 of the CCD 102 is readingthe image area A0 of the original 21. Therefore the signal b0corresponding to the pixel P0 of the CCD 102 in the first period of thefour divided periods includes an image component a0-1 corresponding tothe image area A0 of the original 21.

The CCD 102 stands still and in a second period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0, thepixel P0 of the CCD 102 is reading the image area A0 of the original 21.Therefore the signal b0 corresponding to the pixel P0 of the CCD 102 inthe second period of the four divided periods includes an imagecomponent a0-2 corresponding to the image area A0 of the original 21.

The CCD 102 stands still and in a third period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0, thepixel P0 of the CCD 102 is reading the image area A0 of the original 21.Therefore the signal b0 corresponding to the pixel P0 of the CCD 102 inthe third period of the four divided periods includes an image componenta0-3 corresponding to the image area A0 of the original 21.

The CCD 102 stands still and in a fourth period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0, thepixel P0 of the CCD 102 is reading the image area A0 of the original 21.Therefore the signal b0 corresponding to the pixel P0 of the CCD 102 inthe fourth period of the four divided periods includes an imagecomponent a0-4 corresponding to the image area A0 of the original 21.

Similarly, because the CCD 102 stands still, the signal b4 correspondingto the pixel P0 of the CCD 102 includes image components a0-5 to a0-8corresponding to the image area A0 of the original 21. Because the CCD102 stands still, the signal b8 corresponding to the pixel P0 of the CCD102 includes image components a0-9 to a0-12 corresponding to the imagearea A0 of the original 21. Because the CCD 102 stands still, the signalb12 corresponding to the pixel P0 of the CCD 102 includes imagecomponents a0-13 to a0-16 corresponding to the image area A0 of theoriginal 21.

Because the CCD 102 stands still, the signals corresponding to the pixelP0 of the CCD 102 comprise only the image components corresponding tothe image area A0 of the original 21.

In the first period of the four divided periods of the exposure time t0from the time 0 to the time t0, the pixel P1 of the CCD 102 is readingthe image area A1 of the original 21. Therefore the signal b1corresponding to the pixel P1 of the CCD 102 in the first period of thefour divided periods includes an image component a1-1 corresponding tothe image area Al of the original 21.

The CCD 102 stands still and in the second period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0, thepixel P1 of the CCD 102 is reading the image area A1 of the original 21.Therefore the signal b1 corresponding to the pixel P1 of the CCD 102 inthe second period of the four divided periods includes an imagecomponent a1-2 corresponding to the image area A1 of the original 21.

The CCD 102 stands still and in the third period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0, thepixel P1 of the CCD 102 is reading the image area A1 of the original 21.Therefore the signal b1 corresponding to the pixel P1 of the CCD 102 inthe third period of the four divided periods includes an image componenta1-3 corresponding to the image area A1 of the original 21.

The CCD 102 stands still and in the fourth period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0, thepixel P1 of the CCD 102 is reading the image area A1 of the original 21.Therefore the signal b1 corresponding to the pixel P1 of the CCD 102 inthe fourth period of the four divided periods includes an imagecomponent a1-4 corresponding to the image area A1 of the original 21.

Similarly, because the CCD 102 stands still, the signal b5 correspondingto the pixel P1 of the CCD 102 includes image components a1-5 to a1-8corresponding to the image area A1 of the original 21. Because the CCD102 stands still, the signal b9 corresponding to the pixel P1 of the CCD102 includes image components a1-9 to a1-12 corresponding to the imagearea A1 of the original 21. Because the CCD 102 stands still, the signalb13 corresponding to the pixel P1 of the CCD 102 includes imagecomponents a1-13 to a1-16 corresponding to the image area A1 of theoriginal 21.

Because the CCD 102 stands still, the signals corresponding to the pixelP1 of the CCD 102 comprise only the image components corresponding tothe image area A1 of the original 21.

In the first period of the four divided periods of the exposure time t0from the time 0 to the time t0, the pixel P2 of the CCD 102 is readingthe image area A2 of the original 21. Therefore the signal b2corresponding to the pixel P2 of the CCD 102 in the first period of thefour divided periods includes an image component a2-1 corresponding tothe image area A2 of the original 21.

The CCD 102 stands still and in the second period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0, thepixel P2 of the CCD 102 is reading the image area A2 of the original 21.Therefore the signal b2 corresponding to the pixel P2 of the CCD 102 inthe second period of the four divided periods includes an imagecomponent a2-2 corresponding to the image area A2 of the original 21.

The CCD 102 stands still and in the third period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0, thepixel P2 of the CCD 102 is reading the image area A2 of the original 21.Therefore the signal b2 corresponding to the pixel P2 of the CCD 102 inthe third period of the four divided periods includes an image componenta2-3 corresponding to the image area A2 of the original 21.

The CCD 102 stands still and in the fourth period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0, thepixel P2 of the CCD 102 is reading the image area A2 of the original 21.Therefore the signal b2 corresponding to the pixel P2 of the CCD 102 inthe fourth period of the four divided periods includes an imagecomponent a2-4 corresponding to the image area A2 of the original 21.

Similarly, because the CCD 102 stands still, the signal b6 correspondingto the pixel P2 of the CCD 102 includes image components a2-5 to a2-8corresponding to the image area A2 of the original 21. Because the CCD102 stands still, the signal b10 corresponding to the pixel P2 of theCCD 102 includes image components a2-9 to a2-12 corresponding to theimage area A2 of the original 21. Because the CCD 102 stands still, thesignal b14 corresponding to the pixel P2 of the CCD 102 includes imagecomponents a2-13 to a2-16 corresponding to the image area A2 of theoriginal 21.

Because the CCD 102 stands still, the signals corresponding to the pixelP2 of the CCD 102 comprise only the image components corresponding tothe image area A2 of the original 21.

In the first period of the four divided periods of the exposure time t0from the time 0 to the time t0, the pixel P3 of the CCD 102 is readingthe image area A3 of the original 21. Therefore the signal b3corresponding to the pixel P3 of the CCD 102 in the first period of thefour divided periods includes an image component a3-1 corresponding tothe image area A3 of the original 21.

The CCD 102 stands still and in the second period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0, thepixel P3 of the CCD 102 is reading the image area A3 of the original 21.Therefore the signal b3 corresponding to the pixel P3 of the CCD 102 inthe second period of the four divided periods includes an imagecomponent a3-2 corresponding to the image area A3 of the original 21.

The CCD 102 stands still and in the third period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0, thepixel P3 of the CCD 102 is reading the image area A3 of the original 21.Therefore the signal b3 corresponding to the pixel P3 of the CCD 102 inthe third period of the four divided periods includes an image componenta3-3 corresponding to the image area A3 of the original 21.

The CCD 102 stands still and in the fourth period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0, thepixel P3 of the CCD 102 is reading the image area A3 of the original 21.Therefore the signal b3 corresponding to the pixel P3 of the CCD 102 inthe fourth period of the four divided periods includes an imagecomponent a3-4 corresponding to the image area A3 of the original 21.

Similarly, because the CCD 102 stands still, the signal b7 correspondingto the pixel P3 of the CCD 102 includes image components a3-5 to a3-8corresponding to the image area A3 of the original 21. Because the CCD102 stands still, the signal b11 corresponding to the pixel P3 of theCCD 102 includes image components a3-9 to a3-12 corresponding to theimage area A3 of the original 21. Because the CCD 102 stands still, thesignal b15 corresponding to the pixel P3 of the CCD 102 includes imagecomponents a3-13 to a3-16 corresponding to the image area A3 of theoriginal 21.

Because the CCD 102 stands still, the signals corresponding to the pixelP3 of the CCD 102 comprise only the image components corresponding tothe image area A3 of the original 21.

On the other hand, FIG. 17 is a diagram showing an example of imagecomponents included in the signals outputted by the CCD 102 when lengthof a read area of the original 21 which length corresponds to movementin an exposure time is four times the length of one pixel of the CCD102.

As in FIG. 16, consideration will be given to dividing the exposure timeinto four equal lengths.

In a first period of the four divided periods of the exposure time t0from the time 0 to the time t0, the pixel P0 of the CCD 102 is readingthe image area A0 of the original 21. Therefore the signal b0corresponding to the pixel P0 of the CCD 102 in the first period of thefour divided periods includes an image component a0-1 corresponding tothe image area A0 of the original 21.

The CCD 102 moves relative to the original 21 and in a second period ofthe four divided periods of the exposure time t0 from the time 0 to thetime t0, the pixel P0 of the CCD 102 is reading the image area A1 of theoriginal 21. Therefore the signal b0 corresponding to the pixel P0 ofthe CCD 102 in the second period of the four divided periods includes animage component a1-2 corresponding to the image area A1 of the original21.

The CCD 102 moves relative to the original 21 and in a third period ofthe four divided periods of the exposure time t0 from the time 0 to thetime t0, the pixel P0 of the CCD 102 is reading the image area A2 of theoriginal 21. Therefore the signal b0 corresponding to the pixel P0 ofthe CCD 102 in the third period of the four divided periods includes animage component a2-3 corresponding to the image area A2 of the original21.

The CCD 102 moves relative to the original 21 and in a fourth period ofthe four divided periods of the exposure time t0 from the time 0 to thetime t0, the pixel P0 of the CCD 102 is reading the image area A3 of theoriginal 21. Therefore the signal b0 corresponding to the pixel P0 ofthe CCD 102 in the fourth period of the four divided periods includes animage component a3-4 corresponding to the image area A3 of the original21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b4 corresponding to the pixel P0 of the CCD 102 includes imagecomponents a4-5 to a7-8 corresponding to the image areas A4 to A7 of theoriginal 21. Because the CCD 102 moves relative to the original 21, thesignal b8 corresponding to the pixel P0 of the CCD 102 includes imagecomponents a8-9 to a11-12 corresponding to the image areas A8 to A11 ofthe original 21. Because the CCD 102 moves relative to the original 21,the signal b12 corresponding to the pixel P0 of the CCD 102 includesimage components a12-13 to a15-16 corresponding to the image areas A12to A15 of the original 21.

Thus, because the CCD 102 moves relative to the original 21, the signalscorresponding to the pixel P0 of the CCD 102 comprise different imagecomponents corresponding to different areas of the image of the original21.

In the first period of the four divided periods of the exposure time t0from the time 0 to the time t0, the pixel P1 of the CCD 102 is readingthe image area A1 of the original 21. Therefore the signal b1corresponding to the pixel P1 of the CCD 102 in the first period of thefour divided periods includes an image component a1-1 corresponding tothe image area A1 of the original 21.

The CCD 102 moves relative to the original 21 and in the second periodof the four divided periods of the exposure time t0 from the time 0 tothe time t0, the pixel P1 of the CCD 102 is reading the image area A2 ofthe original 21. Therefore the signal b1 corresponding to the pixel P1of the CCD 102 in the second period of the four divided periods includesan image component a2-2 corresponding to the image area A2 of theoriginal 21.

The CCD 102 moves relative to the original 21 and in a third period ofthe four divided periods of the exposure time t0 from the time 0 to thetime t0, the pixel P1 of the CCD 102 is reading the image area A3 of theoriginal 21. Therefore the signal b1 corresponding to the pixel P1 ofthe CCD 102 in the third period of the four divided periods includes animage component a3-3 corresponding to the image area A3 of the original21.

The CCD 102 moves relative to the original 21 and in the fourth periodof the four divided periods of the exposure time t0 from the time 0 tothe time t0, the pixel P1 of the CCD 102 is reading the image area A4 ofthe original 21. Therefore the signal b1 corresponding to the pixel P1of the CCD 102 in the fourth period of the four divided periods includesan image component a4-4 corresponding to the image area A4 of theoriginal 21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b5 corresponding to the pixel P1 of the CCD 102 includes imagecomponents a5-5 to a8-8 corresponding to the image areas A5 to A8 of theoriginal 21. Because the CCD 102 moves relative to the original 21, thesignal b9 corresponding to the pixel P1 of the CCD 102 includes imagecomponents a9-9 to a12-12 corresponding to the image areas A9 to A12 ofthe original 21. Because the CCD 102 moves relative to the original 21,the signal b13 corresponding to the pixel P1 of the CCD 102 includesimage components a13-13 to a16-16 corresponding to the image areas A13to A16 of the original 21.

Because the CCD 102 moves relative to the original 21, the signalscorresponding to the pixel P1 of the CCD 102 comprise different imagecomponents corresponding to different areas of the image of the original21.

In the first period of the four divided periods of the exposure time t0from the time 0 to the time t0, the pixel P2 of the CCD 102 is readingthe image area A2 of the original 21. Therefore the signal b2corresponding to the pixel P2 of the CCD 102 in the first period of thefour divided periods includes an image component a2-1 corresponding tothe image area A2 of the original 21.

The CCD 102 moves relative to the original 21 and in the second periodof the four divided periods of the exposure time t0 from the time 0 tothe time t0, the pixel P2 of the CCD 102 is reading the image area A3 ofthe original 21. Therefore the signal b2 corresponding to the pixel P2of the CCD 102 in the second period of the four divided periods includesan image component a3-2 corresponding to the image area A3 of theoriginal 21.

The CCD 102 moves relative to the original 21 and in the third period ofthe four divided periods of the exposure time t0 from the time 0 to thetime t0, the pixel P2 of the CCD 102 is reading the image area A4 of theoriginal 21. Therefore the signal b2 corresponding to the pixel P2 ofthe CCD 102 in the third period of the four divided periods includes animage component a4-3 corresponding to the image area A4 of the original21.

The CCD 102 moves relative to the original 21 and in the fourth periodof the four divided periods of the exposure time t0 from the time 0 tothe time t0, the pixel P2 of the CCD 102 is reading the image area A5 ofthe original 21. Therefore the signal b2 corresponding to the pixel P2of the CCD 102 in the fourth period of the four divided periods includesan image component a5-4 corresponding to the image area A5 of theoriginal 21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b6 corresponding to the pixel P2 of the CCD 102 includes imagecomponents a6-5 to a9-8 corresponding to the image areas A6 to A9 of theoriginal 21. Because the CCD 102 moves relative to the original 21, thesignal b10 corresponding to the pixel P2 of the CCD 102 includes imagecomponents a10-9 to a13-12 corresponding to the image areas A10 to A13of the original 21. Because the CCD 102 moves relative to the original21, the signal b14 corresponding to the pixel P2 of the CCD 102 includesimage components a14-13 to a17-16 corresponding to the image areas A14to A17 of the original 21.

Because the CCD 102 moves relative to the original 21, the signalscorresponding to the pixel P2 of the CCD 102 comprise different imagecomponents corresponding to different areas of the image of the original21.

In the first period of the four divided periods of the exposure time t0from the time 0 to the time t0, the pixel P3 of the CCD 102 is readingthe image area A3 of the original 21. Therefore the signal b3corresponding to the pixel P3 of the CCD 102 in the first period of thefour divided periods includes an image component a3-1 corresponding tothe image area A3 of the original 21.

The CCD 102 moves relative to the original 21 and in the second periodof the four divided periods of the exposure time t0 from the time 0 tothe time t0, the pixel P3 of the CCD 102 is reading the image area A4 ofthe original 21. Therefore the signal b3 corresponding to the pixel P3of the CCD 102 in the second period of the four divided periods includesan image component a4-2 corresponding to the image area A4 of theoriginal 21.

The CCD 102 moves relative to the original 21 and in the third period ofthe four divided periods of the exposure time t0 from the time 0 to thetime t0, the pixel P3 of the CCD 102 is reading the image area A5 of theoriginal 21. Therefore the signal b3 corresponding to the pixel P3 ofthe CCD 102 in the third period of the four divided periods includes animage component a5-3 corresponding to the image area A5 of the original21.

The CCD 102 moves relative to the original 21 and in the fourth periodof the four divided periods of the exposure time t0 from the time 0 tothe time t0, the pixel P3 of the CCD 102 is reading the image area A6 ofthe original 21. Therefore the signal b3 corresponding to the pixel P3of the CCD 102 in the fourth period of the four divided periods includesan image component a6-4 corresponding to the image area A6 of theoriginal 21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b7 corresponding to the pixel P3 of the CCD 102 includes imagecomponents a7-5 to a10-8 corresponding to the image areas A7 to A10 ofthe original 21. Because the CCD 102 moves relative to the original 21,the signal b11 corresponding to the pixel P3 of the CCD 102 includesimage components a11-9 to a14-12 corresponding to the image areas A11 toA14 of the original 21. Because the CCD 102 moves relative to theoriginal 21, the signal b15 corresponding to the pixel P3 of the CCD 102includes image components a15-13 to a18-16 corresponding to the imageareas A15 to A18 of the original 21.

Because the CCD 102 moves relative to the original 21, the signalscorresponding to the pixel P3 of the CCD 102 comprise different imagecomponents corresponding to different areas of the image of the original21.

In FIG. 17, a0-1 can be represented as a0.

In FIG. 17, a1-1 and a1-2, which are the image components correspondingto the image area A1 of the original 21 and therefore have the samevalue, can be represented as a1.

In FIG. 17, a2-1 to a2-3, which are the image components correspondingto the image area A2 of the original 21 and therefore have the samevalue, can be represented as a2.

In FIG. 17, a3-1 to a3-4, which are the image components correspondingto the image area A3 of the original 21 and therefore have the samevalue, can be represented as a3.

Similarly, the subsequent image components corresponding to the imageareas A4 to A19 of the original 21 can be represented as a4 to a19.

Relations between the signals outputted by the CCD 102 as illustrated inFIG. 15 and the image components as illustrated in FIG. 17 can beexpressed by equations (1).b0=a0+a1+a2+a3b1=a1+a2+a3+a4b2=a2+a3+a4+a5b3=a3+a4+a5+a6b4=a4+a5+a6+a7b5=a5+a6+a7+a8b6=a6+a7+a8+a9b7=a7+a8+a9+a10b8=a8+a9+a10+a11b9=a9+a10+a11+a12b10=a10+a11+a12+a13b11=a11+a12+a13+a14b12=a12+a13+a14+a15b13=a13+a14+a15+a16b14=a14+a15+a16+a17b15=a15+a16+a17+a18   (1)

In the equations (1), b1 to b15 are values of the signals outputted fromthe CCD 102, and a0 to a18 are unknown variables.

The equations (1) as simultaneous equations cannot be solved as they arebecause the number of unknown variables is larger than the number ofequations.

In the equations including b0 to b3, when b0 to b3 are signalscorresponding to the first reading position of the CCD 102, known valuescan be set as the unknown variables a0 to a2.

In this case, the equations including b0 to b3 have four unknownvariables a3 to a6. Hence, the simultaneous equations comprising thefour equations can be solved to obtain values of a3 to a6.

Further, the equations including b4 to b7 can be solved on the basis ofthe calculated values of a4 to a6, whereby values of a7 to a10 can beobtained.

By repeating such processing, values of a3 to a18 can be obtained.

To generalize the above method, supposing that the CCD 102 has detectingelements arranged in the line form of n columns in the sub-scanningdirection and that the original 21 and the CCD 102 are moved relative toeach other by m pixels in an exposure time, a value integrated byaccumulation of charge is divided into m image components, and thus thenumbers of unknown variables and equations of the equation groupconstructed in correspondence with the exposure time are expressed asfollows:

-   -   Number of unknown variables: n+m−1    -   Number of equations: n

When m is 2 or more, the number of unknown variables exceeds the numberof equations, and therefore the equation group cannot be solved. Whenall unknown variables are determined in an equation group immediatelypreceding that of an exposure time of interest, there are m−1 knownvariables in the equation group immediately preceding that of theexposure time of interest. By using the known variables, the number ofunknown variables becomes equal to the number of equations.

Thus, all unknown variables can be determined.

In the above method, when the unknown variables corresponding to thefirst exposure time are determined, accuracy of the known values isimportant. This is because a chain of effects of errors in the firstknown values occurs as in calculating the values of the unknownvariables corresponding to the first exposure time on the basis of theknown values and calculating the values of the unknown variablescorresponding to the next exposure time on the basis of a result of thecalculation.

Accordingly, processing for breaking such a chain of effects isrequired.

FIG. 18 is a diagram of assistance in explaining a concrete example ofprocessing for obtaining known values and breaking a chain of effects oferrors. In FIG. 18, in periods corresponding to image componentsdescribed as “0,” the CCD 102 operates respective electronic shutters ofthe pixels P0 to P3 to thereby sweep out charge accumulated in thephotodiodes.

Specifically, at a start of the fourth period of the four dividedperiods of the exposure time t0 from the time 0 to the time t0 (whenthree fourths of the exposure time t0 has passed), the CCD 102 operatesthe electronic shutter of the pixel P0 and thereby sweeps out chargeaccumulated in the photodiode corresponding to the pixel P0. At a startof the third period of the four divided periods of the exposure time t0from the time 0 to the time t0 (when one half of the exposure time t0has passed), the CCD 102 operates the electronic shutter of the pixel P1and thereby sweeps out charge accumulated in the photodiodecorresponding to the pixel P1. At a start of the second period of thefour divided periods of the exposure time t0 from the time 0 to the timet0 (when one fourth of the exposure time t0 has passed), the CCD 102operates the electronic shutter of the pixel P2 and thereby sweeps outcharge accumulated in the photodiode corresponding to the pixel P2. TheCCD 102 does not operate the electronic shutter of the pixel P3 duringthe first exposure time t0.

Thus, the variables a0 to a2 in the equations corresponding to b0 to b3in the equations (1) are zero, a known value. Therefore a3 to a6 can becalculated on the basis of the equations corresponding to b0 to b3 inthe equations (1).

Further, at a start of the fourth period of the four divided periods ofthe exposure time t0 from the time 3*t0 to the time 4*t0, the CCD 102operates the electronic shutter of the pixel P0 and thereby sweeps outcharge accumulated in the photodiode corresponding to the pixel P0. At astart of the third period of the four divided periods of the exposuretime t0 from the time 3*t0 to the time 4*t0, the CCD 102 operates theelectronic shutter of the pixel P1 and thereby sweeps out chargeaccumulated in the photodiode corresponding to the pixel P1. At a startof the second period of the four divided periods of the exposure time t0from the time 3*t0 to the time 4*t0, the CCD 102 operates the electronicshutter of the pixel P2 and thereby sweeps out charge accumulated in thephotodiode corresponding to the pixel P2. The CCD 102 does not operatethe electronic shutter of the pixel P3 during the exposure time from thetime 3*t0 to the time 4*t0.

Similarly, the variables a12 to a14 in the equations corresponding tob12 to b15 in the equations (1) are zero, a known value. Therefore a15to a18 can be calculated on the basis of the equations corresponding tob12 to b15 in the equations (1).

Thus, effects of errors included in the result obtained by solving theequations corresponding to the first exposure time t0 are eliminated inthe values calculated as solutions of a15 to a18, whereby propagation oferrors can be blocked.

Relations between the signals outputted by the CCD 102 and the imagecomponents as illustrated in FIG. 18 can be expressed by equations (2).b0 =a3b1=a3+a4b2=a3+a4+a5b3=a3+a4+a5+a6b4=a4+a5+a6+a7b5=a5+a6+a7+a8b6=a6+a7+a8+a9b7=a7+a8+a9+a10b8=a8+a9+a10+a11b9=a9+a10+a11+a12b10=a10+a11+a12+a13b11=a11+a12+a13+a14b12=a15b13=a15+a16b14=a15+a16+a17b15=a15+a16+a17+a18   (2)

The equations including b0 to b3 in the equations (2) have four unknownvariables a3 to a6. Hence, the values of a3 to a6 are obtained.

Next, the equations including b4 to b7 are solved on the basis of thecalculated values of a4 to a6, whereby values of a7 to a10 arecalculated. The equations including b8 to b11 are solved on the basis ofthe values of a8 to a10, whereby values of a11 to a14 are calculated.

The equations including b12 to b15 have four unknown variables a15 toa18. Hence, the values of a15 to a18 are obtained without using thevalues of a12 to a14.

FIG. 19 is a diagram showing another concrete example of processing forobtaining known values and breaking a chain of effects of errors. In theexample shown in FIG. 19, a plurality of relative speeds between theoriginal 21 and the CCD 102 are used properly to block the propagationof errors.

In the first exposure time t0, the relative speed between the original21 and the CCD 102 is controlled such that length of a read area of theoriginal 21 which length corresponds to movement in the exposure time t0is the length of one pixel of the CCD.

In the exposure time t0 from the time t0 to the time 2*t0 and theexposure time t0 from the time 2*t0 to the time 3*t0, the relative speedbetween the original 21 and the CCD 102 is controlled such that lengthof a read area of the original which length corresponds to movement inthe exposure time t0 is four times the length of one pixel of the CCD.

In the exposure time t0 from the time 3*t0 to the time 4*t0, therelative speed between the original 21 and the CCD 102 is controlledsuch that length of a read area of the original 21 which lengthcorresponds to movement in the exposure time t0 is the length of onepixel of the CCD.

In a next exposure time t0 and a further exposure time t0, the relativespeed between the original 21 and the CCD 102 is controlled such thatlength of a read area of the original which length corresponds tomovement in the exposure time t0 is four times the length of one pixelof the CCD.

Thus, the relative speed between the original 21 and the CCD 102 iscontrolled according to the passage of the exposure times t0.

Relations between the signals outputted by the CCD 102 and the imagecomponents as illustrated in FIG. 19 can be expressed by equations (3).b0=4*a0b1=4*a1b2=4*a2b3=4*a3b4=a1+a2+a3+a4b5=a2+a3+a4+a5b6=a3+a4+a5+a6b7=a4+a5+a6+a7b8=a5+a6+a7+a8b9=a6+a7+a8+a9b10=a7+a8+a9+a10b11=a8+a9+a10+a11b12=4*a9b13=4*a10b14=4*a11b15=4*a12   (3)

The signals b0 to b3 corresponding to the first exposure time eachcomprise only the image component of an area having the same length asthe length of one pixel of the CCD. Values of a0 to a3 are obtained inthe equations including b0 to b3 in the equations (3).

Then the equations including b4 to b7 are solved on the basis of thecalculated values of a1 to a3, whereby values of a4 to a7 arecalculated. The equations including b8 to b11 are solved on the basis ofthe values of a5 to a7, whereby values of a8 to a11 are calculated.

The signals b12 to b15 corresponding to the exposure time from the time3*t0 to the time 4*t0 each comprise only the image component of an areahaving the same length as the length of one pixel of the CCD. Values ofa9 to a12 are obtained in the equations including b12 to b15 in theequations (3).

Thus, although the control of the relative speed between the original 21and the CCD 102 becomes complex, charge accumulation time is lengthened,and therefore S/N and accuracy of the calculated image data are improvedas compared with the case shown in FIG. 18.

Description will next be made of a case where an exposure time is t1 andlength of a read area of the original moved in the exposure time t1 ischanged.

The description will be made by taking as an example a case where theexposure time of the CCD 102 is t1 as different from t0, the movingspeed of the CCD 102 is v1 as different from v0, and an amount ofmovement corresponding to the exposure time t1 is twice an amount ofmovement corresponding to the exposure time t0 described with referenceto FIGS. 14 to 19.

As shown in FIG. 20, the amount of movement corresponding to theexposure time t1 is twice the amount of movement corresponding to theexposure time t0, and therefore length of a read area of the original 21in correspondence with movement in the exposure time t1 is eight timesthe length of one pixel of the CCD.

Each of image areas C0 to C3 has a length twice that of each of theimage areas A0 to A10.

FIG. 21 is a diagram of assistance in explaining signals outputted bythe CCD 102 when the length of a read area of the original 21 moved inthe exposure time t1 is eight times the length of one pixel of the CCD102.

In an exposure time t1 from a time 0 to a time t1, a signalcorresponding to the pixel P0 of the CCD 102 is b0; a signalcorresponding to the pixel P1 of the CCD 102 is b1; a signalcorresponding to the pixel P2 of the CCD 102 is b2; and a signalcorresponding to the pixel P3 of the CCD 102 is b3.

In an exposure time t1 from the time t1 to a time 2*t1 (time at whichtwice t1 passes from the time 0), a signal corresponding to the pixel P0of the CCD 102 is b4; a signal corresponding to the pixel P1 of the CCD102 is b5; a signal corresponding to the pixel P2 of the CCD 102 is b6;and a signal corresponding to the pixel P3 of the CCD 102 is b7.

In an exposure time t1 from the time 2*t1 to a time 3*t1 (time at whichthree times t1 passes from the time 0), a signal corresponding to thepixel P0 of the CCD 102 is b8; a signal corresponding to the pixel P1 ofthe CCD 102 is b9; a signal corresponding to the pixel P2 of the CCD 102is b10; and a signal corresponding to the pixel P3 of the CCD 102 isb11.

In an exposure time t1 from the time 3*t1 to a time 4*t1 (time at whichfour times t1 passes from the time 0), a signal corresponding to thepixel P0 of the CCD 102 is b12; a signal corresponding to the pixel P1of the CCD 102 is b13; a signal corresponding to the pixel P2 of the CCD102 is b14; and a signal corresponding to the pixel P3 of the CCD 102 isb15.

Similarly, in an exposure time t1 from the time 4*t1 to a time 5*t1(time at which five times t1 passes from the time 0), a signalcorresponding to the pixel P0 of the CCD 102 is b16; a signalcorresponding to the pixel P1 of the CCD 102 is b17; a signalcorresponding to the pixel P2 of the CCD 102 is b18; and a signalcorresponding to the pixel P3 of the CCD 102 is b19.

FIG. 22 is a diagram showing an example of image components included inthe signals outputted by the CCD 102 when length of a read area of theoriginal 21 moved in an exposure time t1 is eight times the length ofone pixel of the CCD 102.

Consideration will be given to dividing the exposure time into fourequal lengths.

In a first period of the four divided periods of the exposure time t1from the time 0 to the time t1, the pixel P0 of the CCD 102 is readingthe image area C0 of the original 21. Therefore the signal b0corresponding to the pixel P0 of the CCD 102 in the first period of thefour divided periods includes an image component c0-1 corresponding tothe image area C0 of the original 21.

The CCD 102 moves relative to the original 21 and in a second period ofthe four divided periods of the exposure time t1 from the time 0 to thetime t1, the pixel P0 of the CCD 102 is reading the image area C1 of theoriginal 21. Therefore the signal b0 corresponding to the pixel P0 ofthe CCD 102 in the second period of the four divided periods includes animage component c1-2 corresponding to the image area C1 of the original21.

The CCD 102 moves relative to the original 21 and in a third period ofthe four divided periods of the exposure time t1 from the time 0 to thetime t1, the pixel P0 of the CCD 102 is reading the image area C2 of theoriginal 21. Therefore the signal b0 corresponding to the pixel P0 ofthe CCD 102 in the third period of the four divided periods includes animage component c2-3 corresponding to the image area C2 of the original21.

The CCD 102 moves relative to the original 21 and in a fourth period ofthe four divided periods of the exposure time t1 from the time 0 to thetime t1, the pixel P0 of the CCD 102 is reading the image area C3 of theoriginal 21. Therefore the signal b0 corresponding to the pixel P0 ofthe CCD 102 in the fourth period of the four divided periods includes animage component c3-4 corresponding to the image area C3 of the original21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b4 corresponding to the pixel P0 of the CCD 102 includes imagecomponents c4-5 to c7-8 corresponding to image areas C4 to C7 of theoriginal 21. Because the CCD 102 moves relative to the original 21, thesignal b8 corresponding to the pixel P0 of the CCD 102 includes imagecomponents c8-9 to c11-12 corresponding to image areas C8 to C11 of theoriginal 21. Because the CCD 102 moves relative to the original 21, thesignal b12 corresponding to the pixel P0 of the CCD 102 includes imagecomponents c12-13 to c15-16 corresponding to image areas C12 to C15 ofthe original 21. Because the CCD 102 moves relative to the original 21,the signal b16 corresponding to the pixel P0 of the CCD 102 includesimage components c16-17 to c19-20 corresponding to image areas C16 toC19 of the original 21.

Thus, because the CCD 102 moves relative to the original 21, the signalscorresponding to the pixel P0 of the CCD 102 comprise different imagecomponents corresponding to different areas of the image of the original21.

In the first period of the four divided periods of the exposure time t1from the time 0 to the time t1, the pixel P1 of the CCD 102 is readingthe image area C1 of the original 21. Therefore the signal b1corresponding to the pixel P1 of the CCD 102 in the first period of thefour divided periods includes an image component c1-1 corresponding tothe image area C1 of the original 21.

The CCD 102 moves relative to the original 21 and in the second periodof the four divided periods of the exposure time t1 from the time 0 tothe time t1, the pixel P1 of the CCD 102 is reading the image area C2 ofthe original 21. Therefore the signal b1 corresponding to the pixel P1of the CCD 102 in the second period of the four divided periods includesan image component c2-2 corresponding to the image area C2 of theoriginal 21.

The CCD 102 moves relative to the original 21 and in the third period ofthe four divided periods of the exposure time t1 from the time 0 to thetime t1, the pixel P1 of the CCD 102 is reading the image area C3 of theoriginal 21. Therefore the signal b1 corresponding to the pixel P1 ofthe CCD 102 in the third period of the four divided periods includes animage component c3-3 corresponding to the image area C3 of the original21.

The CCD 102 moves relative to the original 21 and in the fourth periodof the four divided periods of the exposure time t1 from the time 0 tothe time t1, the pixel P1 of the CCD 102 is reading the image area C4 ofthe original 21. Therefore the signal b1 corresponding to the pixel P1of the CCD 102 in the fourth period of the four divided periods includesan image component c4-4 corresponding to the image area C4 of theoriginal 21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b5 corresponding to the pixel P1 of the CCD 102 includes imagecomponents c5-5 to c8-8 corresponding to the image areas C5 to C8 of theoriginal 21. Because the CCD 102 moves relative to the original 21, thesignal b9 corresponding to the pixel P1 of the CCD 102 includes imagecomponents c9-9 to c12-12 corresponding to the image areas C9 to C12 ofthe original 21. Because the CCD 102 moves relative to the original 21,the signal b13 corresponding to the pixel P1 of the CCD 102 includesimage components c13-13 to c16-16 corresponding to the image areas C13to C16 of the original 21. Because the CCD 102 moves relative to theoriginal 21, the signal b17 corresponding to the pixel P1 of the CCD 102includes image components c17-17 to c20-20 corresponding to the imageareas C17 to C20 of the original 21.

Because the CCD 102 moves relative to the original 21, the signalscorresponding to the pixel P1 of the CCD 102 comprise different imagecomponents corresponding to different areas of the image of the original21.

In the first period of the four divided periods of the exposure time t1from the time 0 to the time t1, the pixel P2 of the CCD 102 is readingthe image area C2 of the original 21. Therefore the signal b2corresponding to the pixel P2 of the CCD 102 in the first period of thefour divided periods includes an image component c2-1 corresponding tothe image area C2 of the original 21.

The CCD 102 moves relative to the original 21 and in the second periodof the four divided periods of the exposure time t1 from the time 0 tothe time t1, the pixel P2 of the CCD 102 is reading the image area C3 ofthe original 21. Therefore the signal b2 corresponding to the pixel P2of the CCD 102 in the second period of the four divided periods includesan image component c3-2 corresponding to the image area C3 of theoriginal 21.

The CCD 102 moves relative to the original 21 and in the third period ofthe four divided periods of the exposure time t1 from the time 0 to thetime t1, the pixel P2 of the CCD 102 is reading the image area C4 of theoriginal 21. Therefore the signal b2 corresponding to the pixel P2 ofthe CCD 102 in the third period of the four divided periods includes animage component c4-3 corresponding to the image area C4 of the original21.

The CCD 102 moves relative to the original 21 and in the fourth periodof the four divided periods of the exposure time t1 from the time 0 tothe time t1, the pixel P2 of the CCD 102 is reading the image area C5 ofthe original 21. Therefore the signal b2 corresponding to the pixel P2of the CCD 102 in the fourth period of the four divided periods includesan image component c5-4 corresponding to the image area C5 of theoriginal 21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b6 corresponding to the pixel P2 of the CCD 102 includes imagecomponents c6-5 to c9-8 corresponding to the image areas C6 to C9 of theoriginal 21. Because the CCD 102 moves relative to the original 21, thesignal b10 corresponding to the pixel P2 of the CCD 102 includes imagecomponents c10-9 to c13-12 corresponding to the image areas C10 to C13of the original 21. Because the CCD 102 moves relative to the original21, the signal b14 corresponding to the pixel P2 of the CCD 102 includesimage components c14-13 to c17-16 corresponding to the image areas C14to C17 of the original 21. Because the CCD 102 moves relative to theoriginal 21, the signal b18 corresponding to the pixel P2 of the CCD 102includes image components c18-17 to c21-20 corresponding to the imageareas C18 to C21 of the original 21.

Because the CCD 102 moves relative to the original 21, the signalscorresponding to the pixel P2 of the CCD 102 comprise different imagecomponents corresponding to different areas of the image of the original21.

In the first period of the four divided periods of the exposure time t1from the time 0 to the time t1, the pixel P3 of the CCD 102 is readingthe image area C3 of the original 21. Therefore the signal b3corresponding to the pixel P3 of the CCD 102 in the first period of thefour divided periods includes an image component c3-1 corresponding tothe image area C3 of the original 21.

The CCD 102 moves relative to the original 21 and in the second periodof the four divided periods of the exposure time t1 from the time 0 tothe time t1, the pixel P3 of the CCD 102 is reading the image area C4 ofthe original 21. Therefore the signal b3 corresponding to the pixel P3of the CCD 102 in the second period of the four divided periods includesan image component c4-2 corresponding to the image area C4 of theoriginal 21.

The CCD 102 moves relative to the original 21 and in the third period ofthe four divided periods of the exposure time t1 from the time 0 to thetime t1, the pixel P3 of the CCD 102 is reading the image area C5 of theoriginal 21. Therefore the signal b3 corresponding to the pixel P3 ofthe CCD 102 in the third period of the four divided periods includes animage component c5-3 corresponding to the image area C5 of the original21.

The CCD 102 moves relative to the original 21 and in the fourth periodof the four divided periods of the exposure time t1 from the time 0 tothe time t1, the pixel P3 of the CCD 102 is reading the image area C6 ofthe original 21. Therefore the signal b3 corresponding to the pixel P3of the CCD 102 in the fourth period of the four divided periods includesan image component c6-4 corresponding to the image area C6 of theoriginal 21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b7 corresponding to the pixel P3 of the CCD 102 includes imagecomponents c7-5 to c10-8 corresponding to the image areas C7 to C10 ofthe original 21. Because the CCD 102 moves relative to the original 21,the signal b11 corresponding to the pixel P3 of the CCD 102 includesimage components c11-9 to c14-12 corresponding to the image areas C11 toC14 of the original 21. Because the CCD 102 moves relative to theoriginal 21, the signal b15 corresponding to the pixel P3 of the CCD 102includes image components c15-13 to c18-16 corresponding to the imageareas C15 to C18 of the original 21. Because the CCD 102 moves relativeto the original 21, the signal b19 corresponding to the pixel P3 of theCCD 102 includes image components c19-17 to c22-20 corresponding to theimage areas C19 to C22 of the original 21.

Because the CCD 102 moves relative to the original 21, the signalscorresponding to the pixel P3 of the CCD 102 comprise different imagecomponents corresponding to different areas of the image of the original21.

In FIG. 22, c0-1 can be represented as c0.

In FIG. 22, c1-1 and c1-2, which are the image components correspondingto the image area C1 of the original 21 and therefore have the samevalue, can be represented as c1.

In FIG. 22, c2-1 to c2-3, which are the image components correspondingto the image area C2 of the original 21 and therefore have the samevalue, can be represented as c2.

In FIG. 22, c3-1 to c3-4, which are the image components correspondingto the image area C3 of the original 21 and therefore have the samevalue, can be represented as c3.

Similarly, the subsequent image components corresponding to the imageareas C4 to C22 of the original 21 can be represented as c4 to c22.

Relations between the signals outputted by the CCD 102 as illustrated inFIG. 21 and the image components as illustrated in FIG. 22 can beexpressed by equations (4).b0=c0+c1+c2+c3b1=c1+c2+c3+c4b2=c2+c3+c4+c5b3=c3+c4+c5+c6b4=c4+c5+c6+c7b5=c5+c6+c7+c8b6=c6+c7+c8+c9b7=c7+c8+c9+c10b8=c8+c9+c10+c11b9=c9+c10+c11+c12b10=c10+c11+c12+c13b11=c11+c12+c13+c14b12=c12+c13+c14+c15b13=c13+c14+c15+c16b14=c14+c15+c16+c17b15=c15+c16+c17+c18   (4)

In the equations (4), b1 to b15 are values of the signals outputted fromthe CCD 102, and c0 to c18 are unknown variables.

FIG. 23 is a diagram illustrating a concrete example of obtaining knownvalues and breaking a chain of effects of errors. In FIG. 23, in periodscorresponding to image components described as “0,” the CCD 102 operatesthe respective electronic shutters of the pixels P0 to P3 to therebysweep out charge accumulated in the photodiodes.

Specifically, at a start of the fourth period of the four dividedperiods of the exposure time from the time 0 to the time t1 (when threefourths of the exposure time t1 has passed), the CCD 102 operates theelectronic shutter of the pixel P0 and thereby sweeps out chargeaccumulated in the photodiode corresponding to the pixel P0. At a startof the third period of the four divided periods of the exposure timefrom the time 0 to the time t1 (when one half of the exposure time t1has passed), the CCD 102 operates the electronic shutter of the pixel P1and thereby sweeps out charge accumulated in the photodiodecorresponding to the pixel P1. At a start of the second period of thefour divided periods of the exposure time from the time 0 to the time t1(when one fourth of the exposure time t1 has passed), the CCD 102operates the electronic shutter of the pixel P2 and thereby sweeps outcharge accumulated in the photodiode corresponding to the pixel P2. TheCCD 102 does not operate the electronic shutter of the pixel P3 duringthe first exposure time t1.

Thus, the variables c0 to c2 in the equations corresponding to b0 to b3in the equations (4) are zero, a known value. Therefore c3 to c6 can becalculated on the basis of the equations corresponding to b0 to b3 inthe equations (4).

Further, at a start of the fourth period of the four divided periods ofthe exposure time from the time 3*t1 to the time 4*t1, the CCD 102operates the electronic shutter of the pixel P0 and thereby sweeps outcharge accumulated in the photodiode corresponding to the pixel P0. At astart of the third period of the four divided periods of the exposuretime from the time 3*t1 to the time 4*t1, the CCD 102 operates theelectronic shutter of the pixel P1 and thereby sweeps out chargeaccumulated in the photodiode corresponding to the pixel P1. At a startof the second period of the four divided periods of the exposure timefrom the time 3*t1 to the time 4*t1, the CCD 102 operates the electronicshutter of the pixel P2 and thereby sweeps out charge accumulated in thephotodiode corresponding to the pixel P2. The CCD 102 does not operatethe electronic shutter of the pixel P3 during the exposure time from thetime 3*t1 to the time 4*t1.

Similarly, the variables c12 to c14 in the equations corresponding tob12 to b15 in the equations (4) are zero, a known value. Therefore c15to c18 can be calculated on the basis of the equations corresponding tob12 to b15 in the equations (4).

Thus, effects of errors included in the result obtained by solving theequations corresponding to the first exposure time are eliminated in thevalues calculated as solutions of c15 to c18, whereby propagation oferrors can be blocked.

Relations between the signals outputted by the CCD 102 and the imagecomponents as illustrated in FIG. 23 can be expressed by equations (5).b0=c3b1=c3+c4b2=c3+c4+c5b3=c3+c4+c5+c6b4=c4+c5+c6+c7b5=c5+c6+c7+c8b6=c6+c7+c8+c9b7=c7+c8+c9+c10b8=c8+c9+c10+c11b9=c9+c10+c11+c12b10=c10+c11+c12+c13b11=c11+c12+c13+c14b12=c15b13=c15+c16b14=c15+c16+c17b15=c15+c16+c17+c18   (5)

The equations including b0 to b3 in the equations (5) have four unknownvariables c3 to c6. Hence, the values of c3 to c6 are obtained.

Next, the equations including b4 to b7 are solved on the basis of thecalculated values of c4 to c6, whereby values of c7 to c10 arecalculated. The equations including b8 to b11 are solved on the basis ofthe values of c8 to c10, whereby values of c11 to c14 are calculated.

The equations including b12 to b15 have four unknown variables c15 toc18. Hence, the values of c15 to c18 are obtained without using thevalues of c12 to c14.

Description will next be made of processing when the CCD 102 reads theoriginal 21 at a slower speed. The signal processing unit 107 performsthe following processing on the basis of the relative speed between theoriginal 21 and the CCD 102.

FIG. 24 is a diagram showing an example of image components included inthe signals outputted by the CCD 102 when length of a read area of theoriginal 21 which length corresponds to relative movement in an exposuretime t0 is three times the length of one pixel of the CCD 102.

Consideration will be given to dividing the exposure time into threeequal periods.

In a first period of the three divided periods of the exposure time t0from the time 0 to the time t0, the pixel P0 of the CCD 102 is readingthe image area A0 of the original 21. Therefore the signal b0corresponding to the pixel P0 of the CCD 102 in the first period of thethree divided periods includes an image component a0-1 corresponding tothe image area A0 of the original 21.

The CCD 102 moves relative to the original 21 and in a second period ofthe three divided periods of the exposure time t0 from the time 0 to thetime t0, the pixel P0 of the CCD 102 is reading the image area A1 of theoriginal 21. Therefore the signal b0 corresponding to the pixel P0 ofthe CCD 102 in the second period of the three divided periods includesan image component a1-2 corresponding to the image area A1 of theoriginal 21.

The CCD 102 moves relative to the original 21 and in a third period ofthe three divided periods of the exposure time t0 from the time 0 to thetime t0, the pixel P0 of the CCD 102 is reading the image area A2 of theoriginal 21. Therefore the signal b0 corresponding to the pixel P0 ofthe CCD 102 in the third period of the three divided periods includes animage component a2-3 corresponding to the image area A2 of the original21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b4 corresponding to the pixel P0 of the CCD 102 includes imagecomponents a3-4 to a5-6 corresponding to the image areas A3 to A5 of theoriginal 21. Because the CCD 102 moves relative to the original 21, thesignal b8 corresponding to the pixel P0 of the CCD 102 includes imagecomponents a6-7 to a8-9 corresponding to the image areas A6 to A8 of theoriginal 21. Because the CCD 102 moves relative to the original 21, thesignal b12 corresponding to the pixel P0 of the CCD 102 includes imagecomponents a9-10 to a11-12 corresponding to the image areas A9 to A11 ofthe original 21.

In the first period of the three divided periods of the exposure time t0from the time 0 to the time t0, the pixel P1 of the CCD 102 is readingthe image area A1 of the original 21. Therefore the signal b1corresponding to the pixel P1 of the CCD 102 in the first period of thethree divided periods includes an image component a1-1 corresponding tothe image area A1 of the original 21.

The CCD 102 moves relative to the original 21 and in the second periodof the three divided periods of the exposure time t0 from the time 0 tothe time t0, the pixel P1 of the CCD 102 is reading the image area A2 ofthe original 21. Therefore the signal b1 corresponding to the pixel P1of the CCD 102 in the second period of the three divided periodsincludes an image component a2-2 corresponding to the image area A2 ofthe original 21.

The CCD 102 moves relative to the original 21 and in the third period ofthe three divided periods of the exposure time t0 from the time 0 to thetime t0, the pixel P1 of the CCD 102 is reading the image area A3 of theoriginal 21. Therefore the signal b1 corresponding to the pixel P1 ofthe CCD 102 in the third period of the three divided periods includes animage component a3-3 corresponding to the image area A3 of the original21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b5 corresponding to the pixel P1 of the CCD 102 includes imagecomponents a4-4 to a6-6 corresponding to the image areas A4 to A6 of theoriginal 21. Because the CCD 102 moves relative to the original 21, thesignal b9 corresponding to the pixel P1 of the CCD 102 includes imagecomponents a7-7 to a9-9 corresponding to the image areas A7 to A9 of theoriginal 21. Because the CCD 102 moves relative to the original 21, thesignal b13 corresponding to the pixel P1 of the CCD 102 includes imagecomponents a10-10 to a12-12 corresponding to the image areas A10 to A12of the original 21.

In the first period of the three divided periods of the exposure time t0from the time 0 to the time t0, the pixel P2 of the CCD 102 is readingthe image area A2 of the original 21. Therefore the signal b2corresponding to the pixel P2 of the CCD 102 in the first period of thethree divided periods includes an image component a2-1 corresponding tothe image area A2 of the original 21.

The CCD 102 moves relative to the original 21 and in the second periodof the three divided periods of the exposure time t0 from the time 0 tothe time t0, the pixel P2 of the CCD 102 is reading the image area A3 ofthe original 21. Therefore the signal b2 corresponding to the pixel P2of the CCD 102 in the second period of the three divided periodsincludes an image component a3-2 corresponding to the image area A3 ofthe original 21.

The CCD 102 moves relative to the original 21 and in the third period ofthe three divided periods of the exposure time t0 from the time 0 to thetime t0, the pixel P2 of the CCD 102 is reading the image area A4 of theoriginal 21. Therefore the signal b2 corresponding to the pixel P2 ofthe CCD 102 in the third period of the three divided periods includes animage component a4-3 corresponding to the image area A4 of the original21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b6 corresponding to the pixel P2 of the CCD 102 includes imagecomponents a5-4 to a7-6 corresponding to the image areas A5 to A7 of theoriginal 21. Because the CCD 102 moves relative to the original 21, thesignal b10 corresponding to the pixel P2 of the CCD 102 includes imagecomponents a8-7 to a10-9 corresponding to the image areas A8 to A10 ofthe original 21. Because the CCD 102 moves relative to the original 21,the signal b14 corresponding to the pixel P2 of the CCD 102 includesimage components a11-10 to a13-12 corresponding to the image areas A11to A13 of the original 21.

Because the CCD 102 moves relative to the original 21 at the slowerspeed, the signals corresponding to the pixel P2 of the CCD 102 comprisefewer image components corresponding to different areas of the image ofthe original 21 as compared with the higher-speed movement.

The signals outputted by the pixel P3 of the CCD 102 are not used.

In FIG. 24, a0-1 can be represented as a0.

In FIG. 24, a1-1 and a1-2, which are the image components correspondingto the image area A1 of the original 21 and therefore have the samevalue, can be represented as a1.

In FIG. 24, a2-1 to a2-3, which are the image components correspondingto the image area A2 of the original 21 and therefore have the samevalue, can be represented as a2.

In FIG. 24, a3-2 to a3-4, which are the image components correspondingto the image area A3 of the original 21 and therefore have the samevalue, can be represented as a3.

Similarly, the subsequent image components corresponding to the imageareas A4 to A13 of the original 21 can be represented as a4 to a13.

Relations between the signals outputted by the CCD 102 as illustrated inFIG. 15 and the image components as illustrated in FIG. 24 can beexpressed by equations (6).b0=a0+a1+a2b1=a1+a2+a3b2=a2+a3+a4b4=a3+a4+a5b5=a4+a5+a6b6=a5+a6+a7b8=a6+a7+a8b9=a7+a8+a9b10=a8+a9+a10b12=a9+a10+a11b13=a10+a11+a12b14=a10+a12+a13   (6)

In the equations (6), b0 to b2, b4 to b6, b8 to b10, and b12 to b14 arevalues of the signals outputted from the CCD 102, and a0 to a13 areunknown variables.

FIG. 25 is a diagram illustrating a concrete example of obtaining knownvalues and breaking a chain of effects of errors. In FIG. 25, in periodscorresponding to image components described as “0,” the CCD 102 operatesthe respective electronic shutters of the pixels P0 to P2 to therebysweep out charge accumulated in the photodiodes.

Specifically, at a start of the third period of the three dividedperiods of the exposure time from the time 0 to the time t0 (when twothirds of the exposure time t0 has passed), the CCD 102 operates theelectronic shutter of the pixel P0 and thereby sweeps out chargeaccumulated in the photodiode corresponding to the pixel P0. At a startof the second period of the three divided periods of the exposure timefrom the time 0 to the time t0 (when one third of the exposure time t0has passed), the CCD 102 operates the electronic shutter of the pixel P1and thereby sweeps out charge accumulated in the photodiodecorresponding to the pixel P1. The CCD 102 does not operate theelectronic shutter of the pixel P2 during the first exposure time t0.

Thus, the variables a0 and a1 in the equations corresponding to b0 to b2in the equations (6) are zero, a known value. Therefore a2 to a4 can becalculated on the basis of the equations corresponding to b0 to b2 inthe equations (6).

Further, at a start of the third period of the three divided periods ofthe exposure time from the time 3*t0 to the time 4*t0, the CCD 102operates the electronic shutter of the pixel P0 and thereby sweeps outcharge accumulated in the photodiode corresponding to the pixel P0. At astart of the second period of the three divided periods of the exposuretime from the time 3*t0 to the time 4*t0, the CCD 102 operates theelectronic shutter of the pixel P1 and thereby sweeps out chargeaccumulated in the photodiode corresponding to the pixel P1. The CCD 102does not operate the electronic shutter of the pixel P2 during theexposure time from the time 3*t0 to the time 4*t0.

Similarly, the variables a9 and a10 in the equations corresponding tob12 to b14 in the equations (6) are zero, a known value. Therefore a11to a13 can be calculated on the basis of the equations corresponding tob12 to b14 in the equations (6).

Thus, effects of errors included in the result obtained by solving theequations corresponding to the first exposure time are eliminated in thevalues calculated as solutions of a11 to a13, whereby propagation oferrors can be blocked.

Relations between the signals outputted by the CCD. 102 and the imagecomponents as illustrated in FIG. 25 can be expressed by equations (7).b0=a2b1=a2+a3b2=a2+a3+a4b4=a3+a4+a5b5=a4+a5+a6b6=a5+a6+a7b8=a6+a7+a8b9=a7+a8+a9b10=a8+a9+a10b12=a11b13=a11+a12b14=a10+a12+a13   (7)

The equations including b0 to b2 in the equations (7) have three unknownvariables a2 to a4. Hence, the values of a2 to a4 are obtained.

Next, the equations including b4 to b6 are solved on the basis of thecalculated values of a3 and a4, whereby values of a5 to a7 arecalculated. The equations including b8 to b10 are solved on the basis ofthe values of a6 and a7, whereby values of a8 to a10 are calculated.

The equations including b12 to b14 have three unknown variables a11 toa13. Hence, the values of a11 to a13 are obtained without using thecalculated values of a9 and a10.

Description will next be made of processing when the CCD 102 reads theoriginal 21 at a still slower speed. The signal processing unit 107performs the following processing on the basis of the relative speedbetween the original 21 and the CCD 102.

FIG. 26 is a diagram showing an example of image components included inthe signals outputted by the CCD 102 when length of a read area of theoriginal 21 moved in an exposure time t0 is twice the length of onepixel of the CCD 102.

Consideration will be given to dividing the exposure time into two equalperiods.

In a first period of the two divided periods of the exposure time t0from the time 0 to the time t0, the pixel P0 of the CCD 102 is readingthe image area A0 of the original 21. Therefore the signal b0corresponding to the pixel P0 of the CCD 102 in the first period of thetwo divided periods includes an image component a0-1 corresponding tothe image area A0 of the original 21.

In the first period of the two divided periods of the exposure time t0from the time 0 to the time t0, the pixel P1 of the CCD 102 is readingthe image area A0 of the original 21. Therefore the signal b1corresponding to the pixel P1 of the CCD 102 in the first period of thetwo divided periods includes an image component a0-1 corresponding tothe image area A0 of the original 21.

The CCD 102 moves relative to the original 21 and in a second period ofthe two divided periods of the exposure time t0 from the time 0 to thetime t0, the pixel P0 of the CCD 102 is reading the image area A1 of theoriginal 21. Therefore the signal b0 corresponding to the pixel P0 ofthe CCD 102 in the second period of the two divided periods includes animage component a1-2 corresponding to the image area A1 of the original21.

The CCD 102 moves relative to the original 21 and in the second periodof the two divided periods of the exposure time t0 from the time 0 tothe time t0, the pixel P1 of the CCD 102 is reading the image area A1 ofthe original 21. Therefore the signal b1 corresponding to the pixel P1of the CCD 102 in the second period of the two divided periods includesan image component a1-2 corresponding to the image area A1 of theoriginal 21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b4 corresponding to the pixel P0 of the CCD 102 includes imagecomponents a2-3 and a3-4 corresponding to the image areas A2 and A3 ofthe original 21. Because the CCD 102 moves relative to the original 21,the signal b5 corresponding to the pixel P1 of the CCD 102 includesimage components a2-3 and a3-4 corresponding to the image areas A2 andA3 of the original 21.

Because the CCD 102 moves relative to the original 21, the signal b8corresponding to the pixel P0 of the CCD 102 includes image componentsa4-5 and a5-6 corresponding to the image areas A4 and A5 of the original21. Because the CCD 102 moves relative to the original 21, the signal b9corresponding to the pixel P1 of the CCD 102 includes image componentsa4-5 and a5-6 corresponding to the image areas A4 and A5 of the original21.

Because the CCD 102 moves relative to the original 21, the signal b12corresponding to the pixel P0 of the CCD 102 includes image componentsa6-7 to a7-8 corresponding to the image areas A6 and A7 of the original21. Because the CCD 102 moves relative to the original 21, the signalb13 corresponding to the pixel P1 of the CCD 102 includes imagecomponents a6-7 to a7-8 corresponding to the image areas A6 and A7 ofthe original 21.

In the first period of the two divided periods of the exposure time fromthe time 0 to the time t0, the pixel P2 of the CCD 102 is reading theimage area A1 of the original 21. Therefore the signal b2 correspondingto the pixel P2 of the CCD 102 in the first period of the two dividedperiods includes an image component a1-1 corresponding to the image areaA1 of the original 21.

In the first period of the two divided periods of the exposure time fromthe time 0 to the time t0, the pixel P3 of the CCD 102 is reading theimage area A1 of the original 21. Therefore the signal b3 correspondingto the pixel P3 of the CCD 102 in the first period of the two dividedperiods includes an image component a1-1 corresponding to the image areaA0 of the original 21.

The CCD 102 moves relative to the original 21 and in the second periodof the two divided periods of the exposure time from the time 0 to thetime t0, the pixel P2 of the CCD 102 is reading the image area A2 of theoriginal 21. Therefore the signal b2 corresponding to the pixel P2 ofthe CCD 102 in the second period of the two divided periods includes animage component a2-2 corresponding to the image area A2 of the original21.

The CCD 102 moves relative to the original 21 and in the second periodof the two divided periods of the exposure time from the time 0 to thetime t0, the pixel P3 of the CCD 102 is reading the image area A2 of theoriginal 21. Therefore the signal b3 corresponding to the pixel P3 ofthe CCD 102 in the second period of the two divided periods includes animage component a2-2 corresponding to the image area A2 of the original21.

Similarly, because the CCD 102 moves relative to the original 21, thesignal b6 corresponding to the pixel P2 of the CCD 102 includes imagecomponents a3-3 and a4-4 corresponding to the image areas A3 and A4 ofthe original 21. Because the CCD 102 moves relative to the original 21,the signal b7 corresponding to the pixel P3 of the CCD 102 includesimage components a3-3 and a4-4 corresponding to the image areas A3 andA4 of the original 21.

Because the CCD 102 moves relative to the original 21, the signal b10corresponding to the pixel P2 of the CCD 102 includes image componentsa5-5 and a6-6 corresponding to the image areas A5 and A6 of the original21. Because the CCD 102 moves relative to the original 21, the signalb11 corresponding to the pixel P3 of the CCD 102 includes imagecomponents a5-5 and a6-6 corresponding to the image areas A5 and A6 ofthe original 21.

Because the CCD 102 moves relative to the original 21, the signal b14corresponding to the pixel P2 of the CCD 102 includes image componentsa7-7 to a8-8 corresponding to the image areas A7 and A8 of the original21. Because the CCD 102 moves relative to the original 21, the signalb15 corresponding to the pixel P3 of the CCD 102 includes imagecomponents a7-7 to a8-8 corresponding to the image areas A7 and A8 ofthe original 21.

Because the CCD 102 moves relative to the original 21 at the slowerspeed, the signals corresponding to the pixel P2 of the CCD 102 comprisefewer image components corresponding to different areas of the image ofthe original 21 as compared with the higher-speed movement.

In FIG. 26, a0-1 can be represented as a0.

In FIG. 26, a1-1 and a1-2, which are the image components correspondingto the image area A1 of the original 21 and therefore have the samevalue, can be represented as a1.

In FIG. 26, a2-2 and a2-3, which are the image components correspondingto the image area A2 of the original 21 and therefore have the samevalue, can be represented as a2.

In FIG. 26, a3-3 and a3-4, which are the image components correspondingto the image area A3 of the original 21 and therefore have the samevalue, can be represented as a3.

Similarly, the subsequent image components corresponding to the imageareas A4 to A8 of the original 21 can be represented as a4 to a8.

Relations between the signals outputted by the CCD 102 as illustrated inFIG. 15 and the image components as illustrated in FIG. 26 can beexpressed by equations (8).b0+b1=2*(a0+a1)b2+b3=2*(a1+a2)b4+b5=2*(a2+a3)b6+b7=2*(a3+a4)b8+b9=2*(a4+a5)b10+b11=2*(a5+a6)b12+b13=2*(a6+a7)b14+b15=2*(a7+a8)  (8)

In the equations (8), b1 to b15 are values of the signals outputted fromthe CCD 102, and a0 to a8 are unknown variables.

FIG. 27 is a diagram illustrating a concrete example of obtaining knownvalues and breaking a chain of effects of errors. In FIG. 27, in periodscorresponding to image components described as “0,” the CCD 102 operatesthe respective electronic shutters of the pixels P0 to P2 to therebysweep out charge accumulated in the photodiodes.

Specifically, at a start of the second period of the two divided periodsof the exposure time from the time 0 to the time t0 (when one half ofthe exposure time t0 has passed), the CCD 102 operates the electronicshutters of the pixel P0 and the pixel P1 and thereby sweeps out chargeaccumulated in the photodiodes corresponding to the pixel P0 and thepixel P1. The CCD 102 does not operate the electronic shutters of thepixel P2 and the pixel P3 during the first exposure time t0.

Thus, the variable a0 in the equations corresponding to b0 to b4 in theequations (8) is zero, a known value. Therefore a1 and a2 can becalculated on the basis of the equations corresponding to b0 to b4 inthe equations (8).

Further, at a start of the second period of the two divided periods ofthe exposure time from the time 3*t0 to the time 4*t0, the CCD 102operates the electronic shutters of the pixel P0 and the pixel P1 andthereby sweeps out charge accumulated in the photodiodes correspondingto the pixel P0 and the pixel P1. The CCD 102 does not operate theelectronic shutters of the pixel P2 and the pixel P3 during the exposuretime from the time 3*t0 to the time 4*t0.

Similarly, the variable a6 in the equations corresponding to b12 to b15in the equations (8) is zero, a known value. Therefore a7 and a8 can becalculated on the basis of the equations corresponding to b12 to b15 inthe equations (8).

Thus, effects of errors included in the result obtained by solving theequations corresponding to the first exposure time are eliminated in thevalues calculated as solutions of a7 and a8, whereby propagation oferrors can be blocked.

Relations between the signals outputted by the CCD 102 and the imagecomponents as illustrated in FIG. 27 can be expressed by equations (9).b0+b1=2*a1b2+b3=2*(a1+a2)b4+b5=2*(a2+a3)b6+b7=2*(a3+a4)b8+b9=2*(a4+a5)b10+b11=2*(a5+a6)b12+b13=2*a7b14+b15=2*(a7+a8)  (9)

The equations including b0 to b3 in the equations (9) have two unknownvariables a1 and a2. Hence, the values of a1 and a2 are obtained.

Next, the equations including b4 to b7 are solved on the basis of thecalculated value of a2, whereby values of a3 and a4 are calculated. Theequations including b8 to b11 are solved on the basis of the value ofa4, whereby values of a5 and a6 are calculated.

The equations including b12 to b15 have two unknown variables a7 and a8.Hence, the values of a7 and a8 are obtained without using the calculatedvalue of a6.

Reading processing of the scanner or the image reading apparatusaccording to the present invention will next be described with referenceto a flowchart of FIG. 28.

At a step S11, the main CPU 111 controls the driving unit not shown tomove the CCD 102 and a reading area of the original 21 relatively toeach other. For example, the main CPU 111 moves the CCD 102 and thereading area of the original 21 relatively to each other at the speeddescribed with reference to FIG. 19.

At a step S12, the lens 12 condenses light corresponding to the readingarea of the original 21 which light is reduced by the iris 101 on theCCD 102, and forms an image corresponding to the reading area of theoriginal 21 on the CCD 102. At a step S13, the CCD 102 controls theelectronic shutters to convert the incident light into charge. The CCD102 further converts the converted charge into a voltage signal, andthen supplies the obtained signal to the gain adjustment/noisesuppression unit 104. The CCD 102 for example operates the electronicshutter for each pixel in the timing described with reference to FIG. 18on the basis of the driving signal supplied from the timing generator103.

At a step S14, the gain adjustment/noise suppression unit 104 adjustsgain of the signal supplied from the CCD 102, and suppresses noise suchas 1/f noise or the like by applying correlated double samplingprocessing, for example. At a step S15, the A/D conversion unit 105subjects the signal obtained by adjusting the gain and suppressing thenoise to analog/digital conversion, and thereby generates a digitalsignal.

At a step S16, the A/D conversion unit 105 stores the one-dimensionaldigital signal in the memory 106. Incidentally, the A/D conversion unit105 may store the digital signal in the memory 108.

At a step S17, the main CPU 111 determines whether or not scanning ofthe entire image surface of the original 21 is completed on the basis ofa signal indicating the position of the CCD 102, for example. When themain CPU 111 determines that the scanning of the entire image surface ofthe original 21 is not completed, a next area of the original 21 needsto be read, and therefore the processing returns to the step 11 torepeat the reading processing.

When the main CPU 111 determines at the step S17 that the scanning ofthe entire image surface of the original 21 is completed, since theentire image surface of the original 21 is read and two-dimensionalimage data is formed, the processing proceeds to a step S18. The signalprocessing unit 107 applies image signal processing to the image datastored in the memory 106. The image signal processing will be describedlater in detail.

At a step S19, the signal processing unit 107 stores the image data towhich the signal processing has been applied in the memory 110 or makesthe data transmission unit 109 transmit the image data, whereby theprocessing is ended.

FIG. 29 is a flowchart of assistance in explaining details of the imagesignal processing corresponding to the step S18.

At a step S31, the defect correction unit 151 detects a position of aflawed or defective pixel of the input image data, and corrects theflawed or defective pixel by setting an adjacent pixel value in theflawed or defective pixel, for example. At a step S32, the clamp unit152 sets a setup level of a luminance signal of the image data, andclamps the image data.

At a step S33, the white balance unit 153 adjusts RGB gain incorrespondence with a predetermined color temperature, and therebyadjusts white balance of the image data.

At a step S34, the movement blur removing unit 154 removes movement blurincluded in the image data. The movement blur removal processing will bedescribed later in detail.

At a step S35, the gamma correction unit 155 applies gamma correctionfor adjusting level of the image data corresponding to intensity oflight of the CCD 102 to the image data without the movement blur.

At a step S36, the image quality adjustment unit 156 applies processingfor visually improving the image, for example contour correctionprocessing and other image quality adjustment processing to the imagedata.

At a step S37, the color space conversion unit 157 converts a colorspace according to an output format of the image data. Then theprocessing is ended.

The movement blur removal processing corresponding to the step S34 willnext be described with reference to a flowchart of FIG. 30.

At a step S51, the processing unit extracting unit 171 extracts aprocessing unit comprising a predetermined number of pixels from theimage data. For example, the processing unit extracting unit 171extracts b0 to b11 shown in FIG. 15 as a processing unit.

At a step S52, the modeling unit 172 generates a model for dividing asignal integrated in an exposure time in a time direction from therelative speed between the original 21 and the CCD 102 on the basis ofthe processing unit supplied from the processing unit extracting unit171. For example, the modeling unit 172 generates a model that indicatesa relation between the number of pixels of the image data generated as aresult of removing movement blur and the number of pixels included inthe processing unit.

At a step S53, the equation constructing unit 173 constructs equationsfor calculating pixel values of the image data without movement blur onthe basis of the generated model and the extracted processing unit.

At a step S54, the simultaneous equation calculating unit 174 calculatesthe simultaneous equations supplied from the equation constructing unit173, thereby solves the simultaneous equations and calculates imagecomponents. Specifically, the simultaneous equation calculating unit 174corrects gain of the calculated image components according to the numberof divisions of the exposure time, and sets the gain-corrected imagecomponents as pixel values of the image data. Thus, the simultaneousequation calculating unit 174 removes movement blur from the image data,and then outputs the image data without movement blur.

At a step S55, the movement blur removing unit 154 determines whether ornot the processing for the entire image surface is completed on thebasis of a position of the extracted processing unit with respect to theimage surface, for example. When the movement blur removing unit 154determines that the processing for the entire image surface is notcompleted, the processing returns to the step S51 to extract anotherprocessing unit and repeat the movement blur removing processing.

When the movement blur removing unit 154 determines at the step S55 thatthe processing for the entire image surface is completed, the processingis ended.

Thus, the scanner according to the present invention can calculate imagecomponents and remove movement blur from read images.

S/N of the calculated image components is a better value than S/N of animage picked up by the CCD 102 at each original area corresponding to animage component. This is because when an electronic shutter is operatedat each original area corresponding to an image component for imagepickup, the image pickup needs to be performed in a very short exposuretime and consequently the picked-up image includes a large amount ofnoise.

When the scanner has a mechanical shutter and performs image pickup bythe mechanical shutter, the number of shutter operations is reduced,thus decreasing load on the mechanism and hence decreasing failures.

Further, because it is not necessary to stop the CCD 102 at eachoriginal area, the time required to pick up an image of a desired areaof a subject is shortened as compared with the conventional apparatus.

FIG. 31 is a block diagram showing another functional configuration ofthe movement blur removing unit 154.

A processing unit extracting unit 301 extracts a processing unitcomprising predetermined pixels of image data in correspondence withtiming of the electronic shutters of the CCD 102 or the like. Theprocessing unit extracting unit 301 supplies the extracted processingunit to a modeling unit 302.

The modeling unit 302 generates a model on the basis of the processingunit supplied from the processing unit extracting unit 301, and thensupplies the processing unit together with the generated model to anequation constructing unit 303. The model generated by the modeling unit302 for example indicates the number of image components withoutmovement blur included in pixels and the number of pixels included inthe processing unit.

The equation constructing unit 303 applies a method of least squares andthereby constructs equations for calculating image components free frommovement blur on the basis of the model and the processing unit suppliedfrom the modeling unit 302. The equation constructing unit 303 suppliesthe constructed equations to a least square calculating unit 304.

The least square calculating unit 304 solves the equations supplied fromthe equation constructing unit 303, and thereby calculates the imagecomponents without movement blur. The least square calculating unit 304corrects gain of the calculated image components according to the numberof image components included in a pixel value, and sets thegain-corrected image components as pixel values of the image data. Theleast square calculating unit 304 outputs the image data withoutmovement blur.

As described with reference to the equations (1), when all unknownvariables are determined in an equation group immediately preceding thatof an exposure time of interest, there are m−1 known variables in theequation group immediately preceding that of the exposure time ofinterest. By using the known variables, the number of unknown variablesbecomes equal to the number of equations. Thus, all unknown variablescan be determined.

However, the above method cannot be said to be resistant to disturbancesuch as noise because when a large error occurs in a calculationcorresponding to some exposure time, errors are caused in results ofcalculations corresponding to subsequent exposure times.

Accordingly, a method is proposed which provides more accurate resultseven under disturbances by controlling timing of the shutters of the CCD102 for each detecting element (pixel).

FIG. 32 and FIG. 33 are diagrams of assistance in explaining a concreteexample of processing for controlling the timing of the shutters of theCCD 102 for each detecting element and calculating image components.Thick lines in FIG. 32 and FIG. 33 indicate the timing of operation ofthe electronic shutters by the CCD 102.

FIG. 32 is a diagram showing image components included in signalsoutputted by the CCD 102. FIG. 33 is a diagram showing the signalsoutputted by the CCD 102.

Specifically, the CCD 102 does not operate the electronic shutter of thepixel P0 during a first exposure time t0, and operates the electronicshutter at a time t0. The CCD 102 makes the pixel P0 output a signal b0including image components a0-1 to a3-4 at the time t0.

At a start of a fourth period of four divided periods of the exposuretime t0 from a time 0 to the time t0 (when three fourths of the exposuretime t0 has passed), the CCD 102 operates the electronic shutter of thepixel P1 to output a signal b1 corresponding to exposure until thepassage of three fourths of the exposure time t0 from the time 0. Thesignal b1 includes image components a1-1 to a3-3.

At the time t0, the CCD 102 operates the electronic shutter of the pixelP1 to output a signal b4 corresponding to exposure from a time whenthree fourths of the exposure time t0 has passed to the time t0. Thesignal b4 includes an image component a4-4.

At a start of a third period of the four divided periods of the exposuretime t0 from the time 0 to the time t0 (when one half of the exposuretime t0 has passed), the CCD 102 operates the electronic shutter of thepixel P2 to output a signal b2 corresponding to exposure until thepassage of one half of the exposure time t0 from the time 0. The signalb2 includes image components a2-1 and a3-2.

At the time t0, the CCD 102 operates the electronic shutter of the pixelP2 to output a signal b5 corresponding to exposure from a time when onehalf of the exposure time t0 has passed to the time t0. The signal b5includes image components a4-3 and a5-4.

At a start of a second period of the four divided periods of theexposure time t0 from the time 0 to the time t0 (when one fourth of theexposure time t0 has passed), the CCD 102 operates the electronicshutter of the pixel P3 to output a signal b3 corresponding to exposureuntil the passage of one fourth of the exposure time t0 from the time 0.The signal b3 includes an image component a3-1.

At the time t0, the CCD 102 operates the electronic shutter of the pixelP3 to output a signal b6 corresponding to exposure from a time when onefourth of the exposure time t0 has passed to the time t0. The signal b6includes image components a4-2 to a6-4.

Similarly, in image pickup after the time t0, the CCD 102 does notoperate the electronic shutter of the pixel P0 during an exposure timet0, and operates the electronic shutter when the exposure time t0 haspassed.

In image pickup after the time t0, when three fourths of the exposuretime t0 has passed, the CCD 102 operates the electronic shutter of thepixel P1 to output a signal corresponding to exposure. When one fourthof the exposure time t0 has passed, the CCD 102 operates the electronicshutter of the pixel P1 to output a signal corresponding to exposure.

The CCD 102 alternately repeats the operation of the electronic shutterof the pixel P1 at the time of passage of three fourths of the exposuretime to and the operation of the electronic shutter of the pixel P1 atthe time of passage of one fourth of the exposure time t0.

In image pickup after the time t0, when one half of the exposure time t0has passed, the CCD 102 operates the electronic shutter of the pixel P2to output a signal corresponding to exposure.

The CCD 102 repeats the operation of the electronic shutter of the pixelP2 at the time of passage of one half of the exposure time to.

In image pickup after the time t0, when one fourth of the exposure timet0 has passed, the CCD 102 operates the electronic shutter of the pixelP3 to output a signal corresponding to exposure. When three fourths ofthe exposure time t0 has passed, the CCD 102 operates the electronicshutter of the pixel P3 to output a signal corresponding to exposure.

The CCD 102 alternately repeats the operation of the electronic shutterof the pixel P3 at the time of passage of one fourth of the exposuretime t0 and the operation of the electronic shutter of the pixel P3 atthe time of passage of three fourths of the exposure time t0.

Thus, the number of unknown variables becomes equal to the number ofknown signals, so that the unknown variables can be calculated on thebasis of equations corresponding to the respective known signals.

Relations between the image components as illustrated in FIG. 32 and thesignals as illustrated in FIG. 33 can be expressed by equations (10).b0=a0+a1+a2+a3b1=a1+a2+a3b2=a2+a3b3=a3b4=a4b5=a4+a5b6=a4+a5+a6b7=a4+a5+a6+a7b8=a5+a6+a7b9=a6+a7b10=a7b11=a8b12=a8+a9b13=a8+a9+a10b14=a8+a9+a10+a11b15=a9+a10+a11b16=a10+a11b17=a11b18=a12b19=a12+a13b20=a12+a13+a14b21=a12+a13+a14+a15b22=a13+a14+a15b23=a14+a15b24=a15b25=a16b26=a16+a17b27=a16+a17+a18  (10)

Supposing that the equations corresponding to the signals b4 to b10 formone equation group, there are four unknown variables a4 to a7 and sevenequations in the one equation group.

The equations corresponding to the signals b11 to b17 are set as anequation group, and the method of least squares is applied to theequation group to obtain values of unknown variables a8 to a11.

Thus, by applying the method of least squares to equations correspondingto a group of signals outputted before and after a time corresponding toan exposure time, it is possible to calculate image components withreduced errors.

In this case, since S/N of a signal resulting from a short exposure timeand small accumulated charge is low, by reducing a weight of datacorresponding to a signal resulting from a short exposure time andincreasing a weight of data corresponding to a signal resulting from along exposure time, image components can be calculated with higheraccuracy.

The method of least squares will be described briefly in the following.

Supposing that an unknown quantity W acts on an input value X to therebyprovide an observed value Y, an observation equation as represented byan equation (11) is obtained.

$\begin{matrix}{{XW} = Y} & (11) \\{{X = \begin{bmatrix}X_{11} & X_{12} & \ldots & X_{1m} \\X_{21} & X_{22} & \ldots & X_{2m} \\\ldots & \ldots & \ldots & \ldots \\X_{n\; 1} & X_{n\; 2} & \ldots & X_{n\; m}\end{bmatrix}},\mspace{14mu}{W = \begin{bmatrix}W_{1} \\W_{2} \\\ldots \\W_{m}\end{bmatrix}},\mspace{11mu}{Y = \begin{bmatrix}y_{1} \\y_{2} \\\ldots \\y_{n}\end{bmatrix}}} & (12)\end{matrix}$

where m<n in the equation (12).

In consideration of an error included in the observed value Y, theequation (11) can be expressed by a residual equation (13).

$\begin{matrix}{{XW} = {Y + E}} & (13) \\{E = \begin{bmatrix}e_{1} \\e_{2} \\\ldots \\e_{n}\end{bmatrix}} & (14)\end{matrix}$

In order to find the most probable value of the unknown quantity W_(j)(j=1, 2 . . . , m) from the equation (13), it suffices to find W₁, W₂, .. . , W_(m) that satisfy a condition for minimizing an equation (15),that is, an equation (16).

$\begin{matrix}{\sum\limits_{i = 1}^{n}e_{i}^{2}} & (15) \\{{{e_{1}\frac{\partial e_{1}}{\partial w_{j}}} + {e_{2}\frac{\partial e_{2}}{\partial w_{j}}} + \ldots + {e_{n}\frac{\partial e_{n}}{\partial w_{j}}}} = {0\left( {{j = 1},2,\ldots\mspace{14mu},m} \right)}} & (16)\end{matrix}$

Equations (17) are derived from the equation (14).

$\begin{matrix}{{\frac{\partial e_{i}}{\partial w_{1}} = X_{i\; 1}},{\frac{\partial e_{2}}{\partial w_{2}} = X_{i\; 2}},\ldots\mspace{14mu},{\frac{\partial e_{i}}{\partial w_{m}} = {X_{im}\left( {{i = 1},2,\ldots\mspace{14mu},n} \right)}}} & (17)\end{matrix}$

When equations are set up for j=1, 2, . . . , m from the condition ofthe equation (16), equations (18) are obtained.

$\begin{matrix}{{{\sum\limits_{i = 1}^{n}{e_{i}X_{i\; 1}}} = 0},{{\sum\limits_{i = 1}^{n}{e_{i}X_{i\; 2}}} = 0},\ldots\mspace{14mu},{{\sum\limits_{i = 1}^{n}{e_{i}X_{im}}} = 0}} & (18)\end{matrix}$

From the equation (14) and the equations (18), normal equationsrepresented by equations (19) are obtained.

$\quad\begin{matrix}\left\{ \begin{matrix}{{{\left( {\sum\limits_{i = 1}^{n}{X_{i\; 1}X_{i\; 1}}} \right)w_{1}} + {\left( {\sum\limits_{i = 1}^{n}{X_{i\; 1}X_{i\; 2}}} \right)w_{2}} + \ldots + {\left( {\sum\limits_{i = 1}^{n}{X_{i\; 1}X_{im}}} \right)w_{m}}} = \left( {\sum\limits_{i = 1}^{n}{X_{i\; 1}y_{i}}} \right)} \\{{{\left( {\sum\limits_{i = 1}^{n}{X_{i\; 2}X_{i\; 1}}} \right)w_{1}} + {\left( {\sum\limits_{i = 1}^{n}{X_{i\; 2}X_{i\; 2}}} \right)w_{2}} + \ldots + {\left( {\sum\limits_{i = 1}^{n}{X_{i\; 2}X_{im}}} \right)w_{m}}} = \left( {\sum\limits_{i = 1}^{n}{X_{i\; 2}y_{i}}} \right)} \\\ldots \\{{{\left( {\sum\limits_{i = 1}^{n}{X_{im}X_{i\; 1}}} \right)w_{1}} + {\left( {\sum\limits_{i = 1}^{n}{X_{im}X_{i\; 2}}} \right)w_{2}} + \ldots + {\left( {\sum\limits_{i = 1}^{n}{X_{im}X_{im}}} \right)w_{m}}} = \left( {\sum\limits_{i = 1}^{n}{X_{im}y_{i}}} \right)}\end{matrix} \right. & (19)\end{matrix}$

The normal equations are simultaneous equations comprising the samenumber of equations as the number of unknowns. By solving the normalequations, each w_(j) (j=1, 2, . . . , m) as the most probable value canbe determined.

To be more exact, when a matrix of

$\sum\limits_{i = 1}^{n}{x_{ik}x_{il}}$(where k=1, 2, . . . , m, and 1=1, 2, . . . , m) acting on w_(j) (j=1,2, . . . , m) in the equations (19) is regular, the equations (19) canbe solved.

The least square calculating unit 304 determines the most probable valueby applying a sweep-out method (Gauss-Jordan elimination) or the like tothe equations (19).

For example, normal equations corresponding to the equations of thesignals b4 to b10 in the equations (10) are represented as equations(20).1·a4+0·a5+0·a6+0·a7=b41·a4+1·a5+0·a6+0·a7=b51·a4+1·a5+1·a6+0·a7=b61·a4+1·a5+1·a6+1·a7=b70·a4+1·a5+1·a6+1·a7=b80·a4+0·a5+1·a6+1·a7=b90·a4+0·a5+0·a6+1·a7=b10  (20)

The equations (20) can be represented as XW=Y.

X can be represented as an equation (21); W can be represented as anequation (22); and Y can be represented as an equation (23).

$\begin{matrix}{X = \begin{pmatrix}1 & 0 & 0 & 0 \\1 & 1 & 0 & 0 \\1 & 1 & 1 & 0 \\1 & 1 & 1 & 1 \\0 & 1 & 1 & 1 \\0 & 0 & 1 & 1 \\0 & 0 & 0 & 1\end{pmatrix}} & (21) \\{W = \begin{pmatrix}{a4} \\{a5} \\{a6} \\{a7}\end{pmatrix}} & (22) \\{Y = \begin{pmatrix}{b4} \\{b5} \\{b6} \\{b7} \\{b8} \\{b9} \\{b10}\end{pmatrix}} & (23)\end{matrix}$

X is known, W is unknown, and Y is known.

When the method of least squares is applied to this, an equation (24) isobtained.

$\begin{matrix}{{\begin{pmatrix}4 & 3 & 2 & 1 \\3 & 4 & 3 & 2 \\2 & 3 & 4 & 3 \\1 & 2 & 3 & 4\end{pmatrix}\begin{pmatrix}{a4} \\{a5} \\{a6} \\{a7}\end{pmatrix}} = \begin{pmatrix}{{b4} + {b5} + {b6} + {b7}} \\{{b5} + {b6} + {b7} + {b8}} \\{{b6} + {b7} + {b8} + {b9}} \\{{b7} + {b8} + {b9} + {b10}}\end{pmatrix}} & (24)\end{matrix}$

An equation (25) represents an example of an observation equation XW=Ywhen weighting corresponding to exposure times is performed.

$\begin{matrix}{{\begin{pmatrix}1 & 0 & 0 & 0 \\1 & 1 & 0 & 0 \\1 & 1 & 0 & 0 \\1 & 1 & 1 & 0 \\1 & 1 & 1 & 0 \\1 & 1 & 1 & 0 \\1 & 1 & 1 & 1 \\1 & 1 & 1 & 1 \\1 & 1 & 1 & 1 \\1 & 1 & 1 & 1 \\0 & 1 & 1 & 1 \\0 & 1 & 1 & 1 \\0 & 1 & 1 & 1 \\0 & 0 & 1 & 1 \\0 & 0 & 1 & 1 \\0 & 0 & 0 & 1\end{pmatrix}\begin{pmatrix}{a4} \\{a5} \\{a6} \\{a7}\end{pmatrix}} = \begin{pmatrix}{b4} \\{b5} \\{b5} \\{b6} \\{b6} \\{b6} \\{b7} \\{b7} \\{b7} \\{b7} \\{b8} \\{b8} \\{b8} \\{b9} \\{b9} \\{b10}\end{pmatrix}} & (25)\end{matrix}$

X can be represented as an equation (26); W can be represented as anequation (27); and Y can be represented as an equation (28).

$\begin{matrix}{X = \begin{pmatrix}1 & 0 & 0 & 0 \\1 & 1 & 0 & 0 \\1 & 1 & 0 & 0 \\1 & 1 & 1 & 0 \\1 & 1 & 1 & 0 \\1 & 1 & 1 & 0 \\1 & 1 & 1 & 1 \\1 & 1 & 1 & 1 \\1 & 1 & 1 & 1 \\1 & 1 & 1 & 1 \\0 & 1 & 1 & 1 \\0 & 1 & 1 & 1 \\0 & 1 & 1 & 1 \\0 & 1 & 1 & 1 \\0 & 1 & 1 & 1 \\0 & 1 & 1 & 1\end{pmatrix}} & (26) \\{W = \begin{pmatrix}{a4} \\{a5} \\{a6} \\{a7}\end{pmatrix}} & (27) \\{Y = \begin{pmatrix}{b4} \\{b5} \\{b5} \\{b6} \\{b6} \\{b6} \\{b7} \\{b7} \\{b7} \\{b7} \\{b8} \\{b8} \\{b8} \\{b9} \\{b9} \\{b10}\end{pmatrix}} & (28)\end{matrix}$

When the method of least squares is applied to this, an equation (29) isobtained.

$\begin{matrix}{{\begin{pmatrix}10 & 9 & 7 & 4 \\9 & 12 & 10 & 7 \\7 & 10 & 12 & 9 \\4 & 7 & 9 & 10\end{pmatrix}\begin{pmatrix}{a4} \\{a5} \\{a6} \\{a7}\end{pmatrix}} = \begin{pmatrix}{{b4} + {2{b5}} + {3{b6}} + {4{n7}}} \\{{2{b5}} + {3{b6}} + {4{b7}} + {3{b8}}} \\{{3{b6}} + {4{b7}} + {3{b8}} + {2{b9}}} \\{{4{b7}} + {3{b8}} + {2{b9}} + {b10}}\end{pmatrix}} & (29)\end{matrix}$

By performing weighting corresponding to lengths of the exposure times,it is possible to further reduce effect of noise included in the signalsand thereby obtain image components with higher accuracy.

The timing of the electronic shutters described taking FIG. 32 as anexample is a mere example. Basically, each image component can becalculated when the number of equations is larger than the number ofunknown variables, and therefore various patterns are conceivable as thetiming of the electronic shutters.

FIG. 34 and FIG. 35 are diagrams of assistance in explaining anotherconcrete example of processing for controlling the timing of theshutters of the CCD 102 for each detecting element and calculating imagecomponents. Thick lines in FIG. 34 and FIG. 35 indicate the timing ofoperation of the electronic shutters by the CCD 102.

FIG. 34 is a diagram showing image components included in signalsoutputted by the CCD 102. FIG. 35 is a diagram showing the signalsoutputted by the CCD 102.

Specifically, the CCD 102 does not operate the electronic shutter of thepixel P0 during a first exposure time to, and operates the electronicshutter at a time t0. The CCD 102 makes the pixel P0 output a signal b0including image components a0-1 to a3-4 at the time to.

When one fourth of an exposure time t0 has passed from the time t0, theCCD 102 operates the electronic shutter of the pixel P0 to output asignal b4 corresponding to exposure until the passage of one fourth ofthe exposure time t0 from the time t0. The signal b4 includes an imagecomponent a4-5.

When three fourths of the exposure time t0 has passed from the time 0,the CCD 102 operates the electronic shutter of the pixel P1 to output asignal b1 corresponding to exposure until the passage of three fourthsof the exposure time t0 from the time 0. The signal b1 includes imagecomponents a1-1 to a3-3.

When one half of the exposure time t0 has further passed from the timeof passage of three fourths of the exposure time t0, the CCD 102operates the electronic shutter of the pixel P1 to output a signal b5.The signal b5 includes image components a4-4 and a5-5.

When one half of the exposure time t0 has passed from the time 0, theCCD 102 operates the electronic shutter of the pixel P2 to output asignal b2 corresponding to exposure until the passage of one half of theexposure time t0 from the time 0. The signal b2 includes imagecomponents a2-1 and a3-2.

When three fourths of the exposure time t0 has further passed from thetime of passage of one half of the exposure time t0, the CCD 102operates the electronic shutter of the pixel P2 to output a signal b6.The signal b6 includes image components a4-3 to a6-5.

When one fourth of the exposure time t0 from the time 0 to the time t0has passed, the CCD 102 operates the electronic shutter of the pixel P3to output a signal b3 corresponding to exposure until the passage of onefourth of the exposure time t0 from the time 0. The signal b3 includesan image component a3-1.

When the exposure time t0 has further passed from the time of passage ofone fourth of the exposure time t0, the CCD 102 operates the electronicshutter of the pixel P3 to output a signal b7. The signal b7 includesimage components a4-2 to a7-5.

When one half of the exposure time t0 has further passed, the CCD 102operates the electronic shutters of the pixels P0 to P3 to outputsignals b8 to b11 corresponding to exposure until the passage of onehalf of the exposure time t0. The signal b8 includes image componentsa5-6 and a6-7. The signal b9 includes image components a6-6 and a7-7.The signal b10 includes image components a7-6 and a8-7. The signal b11includes image components a8-6 and a9-7.

Similarly, when an exposure time t0 has passed subsequently, the CCD 102operates the electronic shutter of the pixel P0. The CCD 102 makes thepixel P0 output a signal b12 including image components a7-8 to a10-11.

When one fourth of an exposure time t0 has further passed, the CCD 102operates the electronic shutter of the pixel P0 to output a signal b16corresponding to exposure until the passage of one fourth of theexposure time t0. The signal b16 includes an image component a11-12.

When three fourths of the exposure time t0 has passed from the time ofthe previous operation of the electronic shutter of the pixel P1, theCCD 102 operates the electronic shutter of the pixel P1 to output asignal b13 corresponding to exposure until the passage of three fourthsof the exposure time t0. The signal b13 includes image components a8-8to a10-10.

When one half of the exposure time t0 has further passed, the CCD 102operates the electronic shutter of the pixel P1 to output a signal b17.The signal b17 includes image components a11-11 and a12-12.

When one half of the exposure time t0 has passed from the time of theprevious operation of the electronic shutter of the pixel P2, the CCD102 operates the electronic shutter of the pixel P2 to output a signalb14 corresponding to exposure until the passage of one half of theexposure time t0. The signal b14 includes image components a9-8 anda10-9.

When three fourths of the exposure time t0 has further passed, the CCD102 operates the electronic shutter of the pixel P2 to output a signalb18. The signal b18 includes image components a11-10 to a13-12.

When one fourth of the exposure time t0 has passed from the time of theprevious operation of the electronic shutter of the pixel P3, the CCD102 operates the electronic shutter of the pixel P3 to output a signalb15 corresponding to exposure until the passage of one fourth of theexposure time t0. The signal b15 includes an image component a10-8.

When the exposure time t0 has further passed, the CCD 102 operates theelectronic shutter of the pixel P3 to output a signal b19. The signalb19 includes image components a11-9 to a14-12.

When one half of the exposure time t0 has passed from a time 3*t0, theCCD 102 operates the electronic shutters of the pixels P0 to P3 tooutput signals b20 to b23 corresponding to exposure until the passage ofone half of the exposure time t0. The signal b20 includes imagecomponents a12-13 and a13-14. The signal b21 includes image componentsa13-13 and a14-14. The signal b22 includes image components a14-13 anda15-14. The signal b23 includes image components a15-13 and a16-14.

The CCD 102 repeats the operation of the electronic shutters in thetiming described above to output signals.

Thus, the number of unknown variables is seven for 12 known signals,hence the number of signals exceeding the number of unknown variables.The unknown variables can therefore be calculated on the basis ofequations corresponding to the respective known signals.

Relations between the image components as illustrated in FIG. 34 and thesignals as illustrated in FIG. 35 can be expressed by equations (30).b4=a4b5=a4+a5b6=a4+a5+a6b7=a4+a5+a6+a7b8=a5+a6b9=a6+a7b10=a7+a8b11=a8+a9b12=a7+a8+a9+a10b13=a8+a9+a10b14=a9+a10b15=a10  (30)

The method of least squares can be applied to the equations (30) todetermine values of the image components a4 to a10. Also in this case,weights to be assigned can be varied in correspondence with the exposuretimes of the signals.

More general description will be made of the above processing.

When the CCD 201 has elements such as photodiodes arranged in the lineform of n columns in the direction of relative movement to the original21, the number of equations is basically an integral multiple of n.Specifically, the number of equations becomes twice n by operating allthe electronic shutters once between the stepwise timings of theelectronic shutters as shown in FIG. 34 and FIG. 35. The number ofequations becomes three times n by operating all the electronic shutterstwice between the stepwise timings of the electronic shutters as shownin FIG. 34 and FIG. 35.

The number of unknown variables coincides with the number of imagecomponents sandwiched between the stepwise electronic shutters as shownin FIG. 34. Letting m be the number of image components, an equation(31) needs to hold to determine each image component.k*n≧m  (31)

where k is an integer of 1 or more.

Hence, in modeling image data corresponding to the signals outputtedfrom the CCD 102 and the relative speed between the original 21 and theCCD 102, when the equation (31) is satisfied, image components of theimage of the original 21 can be calculated. Thereby movement blur can beremoved.

The movement blur removal processing corresponding to the step S34 willnext be described with reference to a flowchart of FIG. 36.

At a step S101, the processing unit extracting unit 301 extracts aprocessing unit comprising a predetermined number of pixels from theimage data. For example, the processing unit extracting unit 301extracts b4 to b10 shown in FIG. 33 as a processing unit.

At a step S102, the modeling unit 302 generates a model for dividing asignal integrated in an exposure time in a time direction from therelative speed between the original 21 and the CCD 102 on the basis ofthe processing unit supplied from the processing unit extracting unit301. For example, the modeling unit 302 generates a model that indicatesa relation between the number of pixels of the image data generated as aresult of removing movement blur and the number of pixels included inthe processing unit.

At a step S103, the equation constructing unit 303 constructs equationsas normal equations for calculating pixel values of the image datawithout movement blur on the basis of the generated model and theextracted processing unit.

At a step S104, the least square calculating unit 304 applies thesweep-out method, for example, to the normal equations supplied from theequation constructing unit 303, thereby solves the normal equations andcalculates image components. The least square calculating unit 304corrects gain of the calculated image components according to the numberof divisions of the exposure time, and sets the gain-corrected imagecomponents as pixel values of the image data. Thus, the least squarecalculating unit 304 removes movement blur from the image data, and thenoutputs the image data without movement blur.

At a step S105, the movement blur removing unit 154 determines whetheror not the processing for the entire image surface is completed on thebasis of a position of the extracted processing unit with respect to theimage surface, for example. When the movement blur removing unit 154determines that the processing for the entire image surface is notcompleted, the processing returns to the step S101 to extract anotherprocessing unit and repeat the movement blur removing processing.

When the movement blur removing unit 154 determines at the step S105that the processing for the entire image surface is completed, theprocessing is ended.

Thus, the scanner according to the present invention can calculate imagecomponents and remove movement blur from read images.

S/N of the calculated image components is a better value than S/N of animage picked up by the CCD 102 at each original area corresponding to animage component. This is because when an electronic shutter is operatedat each original area corresponding to an image component for imagepickup, the image pickup needs to be performed in a very short exposuretime and consequently the picked-up image includes a large amount ofnoise.

When the scanner has a mechanical shutter and performs image pickup bythe mechanical shutter, the number of shutter operations is reduced,thus decreasing load on the mechanism and hence decreasing failures.

Further, because it is not necessary to stop the CCD 102 at eachoriginal area, the time required to pick up an image of a desired areaof a subject is shortened as compared with the conventional apparatus.

The present invention has the configuration that applies the method ofleast squares, thereby removes movement blur and does not propagateeffects of noise to subsequent processing. It is thus possible to obtainimages without movement blur stably at all times.

FIG. 37 is a diagram showing a configuration of another embodiment of ascanner according to the present invention.

The scanner whose configuration is shown in FIG. 37 is a so-called sheetfeed scanner having an unmagnification optical system.

A carrying unit 501 carries an original 21 disposed on an originalplaten 41 at a predetermined speed from the left to the right of FIG. 37on the basis of driving force supplied from a driving unit not shown inthe figure.

A rod lens 502 receives light incident thereon which light is appliedfrom an illuminating light source 16 and reflected by a read area of theoriginal 21. On the basis of the light incident on the rod lens 502, therod lens 502 forms an image substantially equal in length to the readarea of the original 21 on a linear image sensor 11.

FIG. 38 is a diagram showing a configuration of a further embodiment ofa scanner according to the present invention.

The scanner whose configuration is shown in FIG. 38 is a so-calledflatbed scanner of an integrated carriage type.

A carriage unit 521 has an illuminating light source 16, a mirror 531, amirror 532, a mirror 533, a lens 12, and a linear image sensor 11incorporated and integrally formed therein. The whole of the carriageunit 521 moves when an original 21 is read.

The illuminating light source 16 irradiates a reading area of theoriginal 21 with light of a predetermined intensity. The mirror 531, themirror 532, and the mirror 533 reflect light applied from theilluminating light source 16 and reflected from the original 21 via anoriginal platen 41, and thereby makes the light incident on the linearimage sensor 11 via the lens 12.

The lens 12 refracts the light reflected by the mirror 531, the mirror532, and the mirror 533, and thereby forms an image corresponding to thereading area of the original 21 on the linear image sensor 11.

The linear image sensor 11 reads the image of the reading area of theoriginal 21 and supplies a signal corresponding to the read image to aprocessing unit 13.

The scanner of the integrated carriage type has characteristics in thatit is difficult to reduce its size but it is easy to maintain precisionof the optical system.

FIG. 39 is a diagram showing a configuration of a further embodiment ofa scanner according to the present invention.

The scanner whose configuration is shown in FIG. 39 is a so-calledflatbed scanner of a moving mirror type.

A carriage unit 551 includes an illuminating light source 16 and amirror 561. A carriage unit 552 includes a mirror 571 and a mirror 572.

When an original 21 is read, the carriage unit 551 and the carriage unit552 move separately from each other in such a manner as to maintain aconstant optical distance between a linear image sensor 11 and a readarea of the original 21.

The mirror 561, the mirror 571, and the mirror 572 reflect light appliedfrom the illuminating light source 16 and reflected from the original 21via an original platen 41, and thereby makes the light incident on thelinear image sensor 11 via a lens 12.

The lens 12 refracts the light reflected by the mirror 561, the mirror571, and the mirror 572, and thereby forms an image corresponding to theread area of the original 21 on the linear image sensor 11.

The linear image sensor 11 reads the image of the read area of theoriginal 21 and supplies a signal corresponding to the read image to aprocessing unit 13.

The scanner of the moving mirror type has characteristics in that it isdifficult to maintain precision of the optical system because of itscomplex mechanism and displacement, play, elasticity of a driving beltand the like but it is easy to reduce the size of the scanner.

Thus, the scanner or the image reading apparatus according to thepresent invention can remove movement blur included in a read image andtherefore output image data with higher resolution or higher accuracy.The relative speed between an original as a subject and a line sensor asa reading sensor can be controlled easily and modeling of movement bluris relatively easy. It can therefore be said that the present inventionhas very high usefulness.

As described above, the present invention makes it possible to realizean image reading apparatus with far higher speed than that of aconventional scanner or other image reading apparatus without decreasingaccuracy and S/N even when read data includes movement blur.

It is to be noted that the image reading apparatus according to thepresent invention is not limited to so-called sheet feed scanners,flatbed scanners, or hand-held scanners, and may be a drum scanner forplate making, a camera type scanner or the like. The drum scanner ischaracterized by using a single element as an image sensor for mainscanning and sub-scanning and having a very high resolution withoutdepending on resolution of the image sensor. The camera type scanner ischaracterized by using a two-dimensional sensor as in a digital cameraand hence having limits in the number of pixels of the sensor and havinglow resolution. The present invention can be applied to both of thescanners to remove movement blur and obtain image data with higherresolution.

Also, the present invention is applicable to both apparatus having asingle function as a scanner and apparatus having other functions, suchas facsimile machines, digital copying apparatus or the like.

It is to be noted that the linear image sensor is not limited to CCD orCMOS sensors, and may be for example such a solid-state image pickupdevice as BBD (Bucket Brigade Device), CID (Charge Injection Device), orCPD (Charge Priming Device). The present invention is not limited by thetype of the linear image sensor.

The series of processes described above can be carried out not only byhardware but also by software. When the series of processes is to becarried out by software, a program forming the software is installedfrom a recording medium (storage medium) onto a computer that isincorporated in dedicated hardware, or a general-purpose personalcomputer or the like that can perform various functions by installingvarious programs thereon, for example.

As shown in FIG. 3, the recording medium (storage medium) is not onlyformed by packaged media distributed to users to provide the programseparately from the computer, the packaged media being formed by themagnetic disk 131 (including flexible disks), the optical disk 132(including CD-ROM (Compact Disc-Read Only Memory) and DVD (DigitalVersatile Disc)), the magneto-optical disk 133 (including MD (Mini-Disc)(trademark)), the semiconductor memory 134 or the like which has theprogram recorded (stored) thereon, but also formed by a ROM (for examplea ROM formed integrally in the signal processing unit 107 formed by anembedded computer), a hard disk or the like which has the programrecorded (stored) thereon and which is provided to the user in a stateof being preincorporated in the computer.

Incidentally, the program for carrying out the series of processesdescribed above may be installed onto a computer via a wired or wirelesscommunication medium such as a local area network, the Internet, ordigital satellite broadcasting via an interface such as a router or amodem as required.

Also, in the present specification, the steps describing the programstored on the recording medium (storage medium) include not onlyprocessing carried out in time series in the described order but alsoprocessing carried out in parallel or individually and not necessarilyin time series.

It is to be noted that in the present specification, a system refers toan apparatus as a whole formed by a plurality of apparatus.

INDUSTRIAL APPLICABILITY

According to the present invention, image data with good S/N and higherresolution can be obtained reliably in a short reading time.

FIG. 1

-   11: OUTPUT-   1-2: MOVEMENT-   13: SUB-SCANNING DIRECTION-   1-4: MAIN SCANNING DIRECTION-   13: PROCESSING UNIT    FIG. 2-   2-1: OUTPUT-   2-2: MOVEMENT-   13: PROCESSING UNIT    FIG. 3-   3-1: DRIVING SIGNAL-   3-2: EXPOSURE TIME-   3-3: EXTERNAL CONTROL SIGNAL-   16: ILLUMINATING LIGHT SOURCE-   103: TIMING GENERATOR-   104: GAIN ADJUSTMENT/NOISE SUPPRESSION UNIT-   105: A/D CONVERSION UNIT-   106: MEMORY-   107: SIGNAL PROCESSING UNIT-   108: MEMORY-   109: DATA TRANSMISSION UNIT-   110: MEMORY-   111: MAIN CPU-   112: CONTROLLER-   113: MOTOR-   114: POWER SUPPLY UNIT-   115: INTERFACE-   121: DRIVE    FIG. 4-   4-1: INPUT-   4-2: OUTPUT-   151: DEFECT CORRECTION UNIT-   152: CLAMP UNIT-   153: WHITE BALANCE UNIT-   154: MOVEMENT BLUR REMOVING UNIT-   155: GAMMA CORRECTION UNIT-   156: IMAGE QUALITY ADJUSTMENT UNIT-   157: COLOR SPACE CONVERSION UNIT    FIG. 5-   5-1: INPUT-   5-2: OUTPUT-   171: PROCESSING UNIT EXTRACTING UNIT-   172: MODELING UNIT-   173: EQUATION CONSTRUCTING UNIT-   174: SIMULTANEOUS EQUATION CALCULATING UNIT    FIG. 6-   6-1: TRAVELING DIRECTION    FIG. 7-   7-1: LENGTH OF ONE CCD PIXEL-   7-2: TRAVELING DIRECTION    FIG. 8-   8-1: LENGTH OF ONE CCD PIXEL-   8-2: EXPOSURE TIME-   8-3: MOVEMENT TIME    FIG. 9-   9-1: LENGTH OF ONE CCD PIXEL-   9-2: SUBJECT-   9-3: EXPOSURE TIME    FIG. 10-   10-1: LENGTH OF ONE CCD PIXEL-   10-2: EXPOSURE TIME    FIG. 11-   11-1: LENGTH OF ONE CCD PIXEL-   11-2: EXPOSURE TIME    FIG. 12-   12-1: TRAVELING DIRECTION    FIG. 13-   13-1: LENGTH OF ONE CCD PIXEL-   13-2: TRAVELING DIRECTION-   13-3: SPEED V0    FIG. 14-   14-1: LENGTH OF ONE CCD PIXEL-   14-2: EXPOSURE TIME    FIG. 15-   15-1: TRAVELING DIRECTION    FIG. 16-   16-1: TRAVELING DIRECTION    FIG. 17-   17-1: TRAVELING DIRECTION    FIG. 18-   18-1: TRAVELING DIRECTION    FIG. 19-   19-1: TRAVELING DIRECTION    FIG. 20-   20-1: AMOUNT OF MOVEMENT CORRESPONDING TO t0-   20-2: TRAVELING DIRECTION-   20-3: SPEED VO-   20-4: AMOUNT OF MOVEMENT CORRESPONDING TO t1-   20-5: SPEED V1    FIG. 21-   21-1: TRAVELING DIRECTION    FIG. 22-   22-1: TRAVELING DIRECTION    FIG. 23-   23-1: TRAVELING DIRECTION    FIG. 24-   24-1: TRAVELING DIRECTION    FIG. 25-   25-1: TRAVELING DIRECTION    FIG. 26-   26-1: TRAVELING DIRECTION    FIG. 27-   27-1: TRAVELING DIRECTION    FIG. 28-   28-1: START READING PROCESSING-   28-2: END-   S11: MOVE CCD AND READING AREA RELATIVELY TO EACH OTHER-   S12: CONDENSE LIGHT-   S13: CONTROL ELECTRONIC SHUTTERS TO CONVERT LIGHT INTO CHARGE-   S14: CONTROL GAIN AND SUPPRESS NOISE-   S15: PERFORM A/D CONVERSION-   S16: STORE DATA IN MEMORY-   S17: IS SCANNING OF ENTIRE IMAGE SURFACE COMPLETED?-   S18: IMAGE SIGNAL PROCESSING-   S19: STORE OR TRANSMIT    FIG. 29-   29-1: START IMAGE SIGNAL PROCESSING-   29-2: RETURN-   S31: DEFECT CORRECTION-   S32: CLAMP-   S33: WHITE BALANCE-   S34: MOVEMENT BLUR REMOVAL-   S35: GAMMA CORRECTION-   S36: IMAGE QUALITY ADJUSTMENT-   S37: COLOR SPACE CONVERSION    FIG. 30-   30-1: START MOVEMENT BLUR REMOVAL PROCESSING-   30-2: RETURN-   S51: EXTRACT PROCESSING UNIT-   S52: GENERATE MODEL-   S53: CONSTRUCT EQUATIONS-   S54: CALCULATE SIMULTANEOUS EQUATIONS-   S55: IS PROCESSING FOR ENTIRE IMAGE SURFACE COMPLETED?    FIG. 31-   31-1: INPUT-   31-2: OUTPUT-   301: PROCESSING UNIT EXTRACTING UNIT-   302: MODELING UNIT-   303: EQUATION CONSTRUCTING UNIT-   304: LEAST SQUARE CALCULATING UNIT    FIG. 32-   32-1: TRAVELING DIRECTION    FIG. 33-   33-1: TRAVELING DIRECTION    FIG. 34-   34-1: TRAVELING DIRECTION    FIG. 35-   35-1: TRAVELING DIRECTION    FIG. 36-   36-1: START MOVEMENT BLUR REMOVAL PROCESSING-   36-2: RETURN-   S101: EXTRACT PROCESSING UNIT-   S102: GENERATE MODEL-   S103: CONSTRUCT EQUATIONS-   S104: PERFORM LEAST SQUARE CALCULATION-   S105: IS PROCESSING FOR ENTIRE IMAGE SURFACE COMPLETED?    FIG. 37-   37-1: OUTPUT-   13: PROCESSING UNIT    FIG. 38-   38-1:. MOVEMENT-   38-2: OUTPUT-   13: PROCESSING UNIT    FIG. 39-   39-1: MOVEMENT-   39-2: OUTPUT-   13: PROCESSING UNIT

1. An image reading apparatus comprising: a reading device formed byarranging line sensors, in which detecting elements having a timeintegration effect are arranged in a direction orthogonal to a relativemovement direction in which the reading means moves relative to anobject being detected, in a plurality of columns in said relativemovement direction; a pixel component detecting device configured todetect pixel components on the basis of a model for separating firstpixel values obtained in a processing unit time by said detectingelements into a plurality of said pixel components corresponding todetection positions of said object being detected; and a pixel valuegenerating device configured to generate second pixel valuescorresponding to said detection positions of said object being detectedon the basis of said pixel components detected by said pixel componentdetecting means, wherein, said pixel component detecting device includesa model generating device for generating said model that represents arelation between said first pixel values and a plurality of said pixelcomponents corresponding to said detection positions, said pixelcomponents being accumulated in each divided unit time obtained bydividing said processing unit time by a number of columns of said linesensors; and wherein said pixel component detecting device is configuredto detect said pixel components on the basis of said model generated bysaid model generating device.
 2. An image reading apparatus as claimedin claim 1, further comprising a speed detecting device configured todetect relative speed between said detecting elements and said objectbeing detected, wherein said model generating device is configured togenerate said model that represents a relation between said first pixelvalues obtained from a part of said detecting elements of said linesensors arranged in said reading device and said pixel components incorrespondence with said relative speed detected by said speed detectingdevice.
 3. An image reading apparatus as claimed in claim 1, furthercomprising a speed detecting device configured to detect relative speedbetween said detecting elements and said object being detected, whereinsaid model generating device is configured to generate said model thatrepresents a relation between third pixel values obtained by addingtogether said first pixel values obtained from adjacent said detectingelements of a plurality of said detecting elements arranged in columnsin said relative movement direction of said reading device and saidpixel components in correspondence with said relative speed detected bysaid speed detecting device.
 4. An image reading apparatus as claimed inclaim 1, further comprising a control device configured to control saidreading means such that when said reading device is positioned at aninitial position, said reading device configured to pick up an image ofsaid object being detected and output said first pixel valuescorresponding to said detecting elements in a state of standing stillwith respect to said object being detected during said processing unittime, wherein said pixel component detecting device is configured todetect other said pixel components by substituting said pixel componentsgenerated on the basis of said first pixel values resulting from imagepickup by said reading device in the state of standing still withrespect to said object being detected under control of said controldevice into said model that represents a relation between said firstpixel values and a plurality of said pixel components corresponding tosaid detection positions.
 5. An image reading apparatus as claimed inclaim 4, characterized in that: said control device is configured tocontrol said reading means such that said reading device is configuredto pick up an image of said object being detected and outputs said firstpixel values corresponding to said detecting elements in the state ofstanding still with respect to said object being detected during saidprocessing unit time at predetermined time intervals.
 6. An imagereading apparatus as claimed in claim 1, further comprising a controldevice is configured to control exposure time for each of said detectingelements of said reading device such that each of said first pixelvalues includes said pixel component corresponding to a differentposition in the relative-movement direction of said object beingdetected, wherein said pixel component detecting device is configured todetect said pixel components on the basis of said model that representsa relation between said first pixel values each including said pixelcomponent corresponding to a different position in the relative movementdirection of said object being detected and a plurality of said pixelcomponents corresponding to said detection positions.
 7. An imagereading apparatus as claimed in claim 6, characterized in that: saidcontrol device is configured to control the exposure time for each ofsaid detecting elements of said reading device such that each of saidfirst pixel values includes said pixel component corresponding to adifferent position in the relative movement direction of said objectbeing detected at predetermined time intervals.
 8. An image readingapparatus as claimed in claim 1, further comprising a moving deviceconfigured to move one of said object being detected and said readingdevice to change a relative position between said object being detectedand said reading device.
 9. An image reading apparatus as claimed inclaim 1, characterized in that: said pixel component detecting deviceincludes a normal equation generating device configured to generate anormal equation on the basis of a model for separating first pixelvalues obtained by said detecting elements into a plurality of pixelcomponents corresponding to detection positions of said object beingdetected; and said pixel component detecting device is configured todetect said pixel components on the basis of said normal equationgenerated by said normal equation generating device.
 10. An imagereading apparatus as claimed in claim 9, further comprising: a firstcontrol device configured to control image pickup of said reading devicesuch that each of said detecting elements arranged in a plurality ofcolumns in said relative movement direction begins exposure at anidentical first position of said detection positions of said objectbeing detected and ends exposure at an identical second positiondifferent from said first position; and a second control deviceconfigured to control the image pickup of said reading device such thatsaid detecting elements begin exposure after ending exposure at a thirdtime between a first time when all of said detecting elements arrangedin the plurality of columns have reached said first position and havebegun exposure and a second time when one of said detecting elementsarranged in the plurality of columns has reached said second positionand has ended exposure; wherein said normal equation generating deviceis configured to generate said normal equation by setting said firstpixel values obtained by said detecting elements in said normal equationrepresenting a relation between a plurality of said pixel componentsincluding said pixel component corresponding to one of said firstposition, said second position, and a third position as said detectionposition at said third time and said first pixel values.
 11. An imagereading apparatus as claimed in claim 9, characterized in that: saidnormal equation generating device is configured to generate said normalequation for calculating said pixel components by applying a method ofleast squares.
 12. An image reading apparatus as claimed in claim 9,characterized in that: said normal equation generating device isconfigured to generate said normal equation weighted in correspondencewith lengths of exposure times for obtaining said first pixel values.13. An image reading method of an image reading apparatus, said imagereading apparatus including a reading device formed by arranging linesensors, in which detecting elements having a time integration effectare arranged in a direction orthogonal to a relative movement directionin which the reading apparatus moves relative to an object beingdetected, in a plurality of columns in said relative movement direction,said image reading method comprising the steps of: detecting pixelcomponents on the basis of a model for separating first pixel valuesobtained in a processing unit time by said detecting elements into aplurality of said pixel components corresponding to detection positionsof said object being detected; and generating second pixel valuescorresponding to said detection positions of said object being detectedon the basis of said pixel components detected by processing of saidpixel component detecting step.
 14. A computer-readable medium encodedwith a computer program, said program being for image reading processingof an image reading apparatus, said image reading apparatus including areading apparatus formed by arranging line sensors, in which detectingelements having a time integration effect are arranged in a directionorthogonal to a relative movement direction in which the readingapparatus moves relative to an object being detected, in a plurality ofcolumns in said relative movement direction, said program comprising thesteps of: detecting pixel components on the basis of a model forseparating first pixel values obtained in a processing unit time by saiddetecting elements into a plurality of said pixel componentscorresponding to detection positions of said object being detected; andgenerating second pixel values corresponding to said detection positionsof said object being detected on the basis of said pixel componentsdetected by processing of said pixel component detecting step.
 15. Acomputer-readable medium encoded with a computer program executable by acomputer, said computer controlling an image reading apparatus, saidimage reading apparatus including a reading apparatus formed byarranging line sensors, in which detecting elements having a timeintegration effect are arranged in a direction orthogonal to a relativemovement direction in which the reading apparatus moves relative to anobject being detected, in a plurality of columns in said relativemovement direction, said program comprising the steps of: detectingpixel components on the basis of a model for separating first pixelvalues obtained in a processing unit time by said detecting elementsinto a plurality of said pixel components corresponding to detectionpositions of said object being detected; and generating second pixelvalues corresponding to said detection positions of said object beingdetected on the basis of said pixel components detected by processing ofsaid pixel component detecting step.